diff --git a/build.zig b/build.zig
index bcf34bee..e5ab3491 100644
--- a/build.zig
+++ b/build.zig
@@ -189,7 +189,7 @@ fn addDependencies(
         .prebuilt_v8_path = prebuilt_v8_path,
         .is_asan = is_asan,
         .is_tsan = is_tsan,
-        .v8_enable_sandbox = is_tsan,
+        .v8_enable_sandbox = is_tsan, // v8 contains a bug and cannot be compiled with tsan without a sandbox.
     };
 
     mod.addIncludePath(b.path("vendor/lightpanda"));
diff --git a/src/ArenaPool.zig b/src/ArenaPool.zig
index f7d7015f..93a3271d 100644
--- a/src/ArenaPool.zig
+++ b/src/ArenaPool.zig
@@ -29,6 +29,7 @@ free_list_len: u16 = 0,
 free_list: ?*Entry = null,
 free_list_max: u16,
 entry_pool: std.heap.MemoryPool(Entry),
+mutex: std.Thread.Mutex,
 
 const Entry = struct {
     next: ?*Entry,
@@ -41,6 +42,7 @@ pub fn init(allocator: Allocator) ArenaPool {
         .free_list_max = 512, //  TODO make configurable
         .retain_bytes = 1024 * 16, // TODO make configurable
         .entry_pool = std.heap.MemoryPool(Entry).init(allocator),
+        .mutex = .{},
     };
 }
 
@@ -54,6 +56,9 @@ pub fn deinit(self: *ArenaPool) void {
 }
 
 pub fn acquire(self: *ArenaPool) !Allocator {
+    self.mutex.lock();
+    defer self.mutex.unlock();
+
     if (self.free_list) |entry| {
         self.free_list = entry.next;
         self.free_list_len -= 1;
@@ -73,6 +78,12 @@ pub fn release(self: *ArenaPool, allocator: Allocator) void {
     const arena: *std.heap.ArenaAllocator = @ptrCast(@alignCast(allocator.ptr));
     const entry: *Entry = @fieldParentPtr("arena", arena);
 
+    // Reset the arena before acquiring the lock to minimize lock hold time
+    _ = arena.reset(.{ .retain_with_limit = self.retain_bytes });
+
+    self.mutex.lock();
+    defer self.mutex.unlock();
+
     const free_list_len = self.free_list_len;
     if (free_list_len == self.free_list_max) {
         arena.deinit();
@@ -80,7 +91,6 @@ pub fn release(self: *ArenaPool, allocator: Allocator) void {
         return;
     }
 
-    _ = arena.reset(.{ .retain_with_limit = self.retain_bytes });
     entry.next = self.free_list;
     self.free_list_len = free_list_len + 1;
     self.free_list = entry;
diff --git a/src/Config.zig b/src/Config.zig
index fc4ebcdd..66e26219 100644
--- a/src/Config.zig
+++ b/src/Config.zig
@@ -30,6 +30,13 @@ pub const RunMode = enum {
     version,
 };
 
+pub const MAX_HTTP_REQUEST_SIZE = 4096;
+
+// max message size
+// +14 for max websocket payload overhead
+// +140 for the max control packet that might be interleaved in a message
+pub const MAX_MESSAGE_SIZE = 512 * 1024 + 14 + 140;
+
 mode: Mode,
 exec_name: []const u8,
 http_headers: HttpHeaders,
@@ -131,6 +138,20 @@ pub fn userAgentSuffix(self: *const Config) ?[]const u8 {
     };
 }
 
+pub fn maxConnections(self: *const Config) u16 {
+    return switch (self.mode) {
+        .serve => |opts| opts.max_connections,
+        else => unreachable,
+    };
+}
+
+pub fn maxPendingConnections(self: *const Config) u31 {
+    return switch (self.mode) {
+        .serve => |opts| opts.max_pending_connections,
+        else => unreachable,
+    };
+}
+
 pub const Mode = union(RunMode) {
     help: bool, // false when being printed because of an error
     fetch: Fetch,
@@ -144,7 +165,6 @@ pub const Serve = struct {
     timeout: u31 = 10,
     max_connections: u16 = 16,
     max_tabs_per_connection: u16 = 8,
-    max_memory_per_tab: u64 = 512 * 1024 * 1024,
     max_pending_connections: u16 = 128,
     common: Common = .{},
 };
@@ -479,19 +499,6 @@ fn parseServeArgs(
             continue;
         }
 
-        if (std.mem.eql(u8, "--max_tab_memory", opt)) {
-            const str = args.next() orelse {
-                log.fatal(.app, "missing argument value", .{ .arg = "--max_tab_memory" });
-                return error.InvalidArgument;
-            };
-
-            serve.max_memory_per_tab = std.fmt.parseInt(u64, str, 10) catch |err| {
-                log.fatal(.app, "invalid argument value", .{ .arg = "--max_tab_memory", .err = err });
-                return error.InvalidArgument;
-            };
-            continue;
-        }
-
         if (std.mem.eql(u8, "--max_pending_connections", opt)) {
             const str = args.next() orelse {
                 log.fatal(.app, "missing argument value", .{ .arg = "--max_pending_connections" });
diff --git a/src/Server.zig b/src/Server.zig
index a557d8ed..b547e4aa 100644
--- a/src/Server.zig
+++ b/src/Server.zig
@@ -28,43 +28,51 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 
 const log = @import("log.zig");
 const App = @import("App.zig");
+const Config = @import("Config.zig");
 const CDP = @import("cdp/cdp.zig").CDP;
-
-const MAX_HTTP_REQUEST_SIZE = 4096;
-
-// max message size
-// +14 for max websocket payload overhead
-// +140 for the max control packet that might be interleaved in a message
-const MAX_MESSAGE_SIZE = 512 * 1024 + 14 + 140;
+const Http = @import("http/Http.zig");
+const HttpClient = @import("http/Client.zig");
 
 const Server = @This();
+
 app: *App,
-shutdown: bool = false,
+shutdown: std.atomic.Value(bool) = .init(false),
 allocator: Allocator,
-client: ?posix.socket_t,
 listener: ?posix.socket_t,
 json_version_response: []const u8,
 
-pub fn init(app: *App, address: net.Address) !Server {
-    const allocator = app.allocator;
+// Thread management
+active_threads: std.atomic.Value(u32) = .init(0),
+clients: std.ArrayListUnmanaged(*Client) = .{},
+clients_mu: std.Thread.Mutex = .{},
+clients_pool: std.heap.MemoryPool(Client),
+
+pub fn init(allocator: Allocator, app: *App, address: net.Address) !Server {
     const json_version_response = try buildJSONVersionResponse(allocator, address);
     errdefer allocator.free(json_version_response);
 
     return .{
         .app = app,
-        .client = null,
         .listener = null,
         .allocator = allocator,
         .json_version_response = json_version_response,
+        .clients_pool = std.heap.MemoryPool(Client).init(allocator),
     };
 }
 
 /// Interrupts the server so that main can complete normally and call all defer handlers.
 pub fn stop(self: *Server) void {
-    if (@atomicRmw(bool, &self.shutdown, .Xchg, true, .monotonic)) {
+    if (self.shutdown.swap(true, .release)) {
         return;
     }
 
+    // Shutdown all active clients
+    self.clients_mu.lock();
+    for (self.clients.items) |client| {
+        client.stop();
+    }
+    self.clients_mu.unlock();
+
     // Linux and BSD/macOS handle canceling a socket blocked on accept differently.
     // For Linux, we use std.shutdown, which will cause accept to return error.SocketNotListening (EINVAL).
     // For BSD, shutdown will return an error. Instead we call posix.close, which will result with error.ConnectionAborted (BADF).
@@ -81,17 +89,18 @@ pub fn stop(self: *Server) void {
 }
 
 pub fn deinit(self: *Server) void {
+    self.joinThreads();
     if (self.listener) |listener| {
         posix.close(listener);
         self.listener = null;
     }
-    // *if* server.run is running, we should really wait for it to return
-    // before existing from here.
+    self.clients.deinit(self.allocator);
+    self.clients_pool.deinit();
     self.allocator.free(self.json_version_response);
 }
 
 pub fn run(self: *Server, address: net.Address, timeout_ms: u32) !void {
-    const flags = posix.SOCK.STREAM | posix.SOCK.CLOEXEC;
+    const flags = posix.SOCK.STREAM | posix.SOCK.CLOEXEC | posix.SOCK.NONBLOCK;
     const listener = try posix.socket(address.any.family, flags, posix.IPPROTO.TCP);
     self.listener = listener;
 
@@ -101,16 +110,20 @@ pub fn run(self: *Server, address: net.Address, timeout_ms: u32) !void {
     }
 
     try posix.bind(listener, &address.any, address.getOsSockLen());
-    try posix.listen(listener, 1);
+    try posix.listen(listener, self.app.config.maxPendingConnections());
 
     log.info(.app, "server running", .{ .address = address });
-    while (!@atomicLoad(bool, &self.shutdown, .monotonic)) {
+    while (!self.shutdown.load(.acquire)) {
         const socket = posix.accept(listener, null, null, posix.SOCK.NONBLOCK) catch |err| {
             switch (err) {
                 error.SocketNotListening, error.ConnectionAborted => {
                     log.info(.app, "server stopped", .{});
                     break;
                 },
+                error.WouldBlock => {
+                    std.Thread.sleep(10 * std.time.ns_per_ms);
+                    continue;
+                },
                 else => {
                     log.err(.app, "CDP accept", .{ .err = err });
                     std.Thread.sleep(std.time.ns_per_s);
@@ -119,97 +132,99 @@ pub fn run(self: *Server, address: net.Address, timeout_ms: u32) !void {
             }
         };
 
-        self.client = socket;
-        defer if (self.client) |s| {
-            posix.close(s);
-            self.client = null;
-        };
-
-        if (log.enabled(.app, .info)) {
-            var client_address: std.net.Address = undefined;
-            var socklen: posix.socklen_t = @sizeOf(net.Address);
-            try std.posix.getsockname(socket, &client_address.any, &socklen);
-            log.info(.app, "client connected", .{ .ip = client_address });
-        }
-
-        self.readLoop(socket, timeout_ms) catch |err| {
-            log.err(.app, "CDP client loop", .{ .err = err });
+        self.spawnWorker(socket, timeout_ms) catch |err| {
+            log.err(.app, "CDP spawn", .{ .err = err });
+            posix.close(socket);
         };
     }
 }
 
-fn readLoop(self: *Server, socket: posix.socket_t, timeout_ms: u32) !void {
-    // This shouldn't be necessary, but the Client is HUGE (> 512KB) because
-    // it has a large read buffer. I don't know why, but v8 crashes if this
-    // is on the stack (and I assume it's related to its size).
-    const client = try self.allocator.create(Client);
-    defer self.allocator.destroy(client);
+fn handleConnection(self: *Server, socket: posix.socket_t, timeout_ms: u32) void {
+    defer posix.close(socket);
 
-    client.* = try Client.init(socket, self);
+    // Client is HUGE (> 512KB) because it has a large read buffer.
+    // V8 crashes if this is on the stack (likely related to its size).
+    const client = self.getClient() catch |err| {
+        log.err(.app, "CDP client create", .{ .err = err });
+        return;
+    };
+    defer self.releaseClient(client);
+
+    client.* = Client.init(
+        socket,
+        self.allocator,
+        self.app,
+        self.json_version_response,
+        timeout_ms,
+    ) catch |err| {
+        log.err(.app, "CDP client init", .{ .err = err });
+        return;
+    };
     defer client.deinit();
 
-    var http = &self.app.http;
-    http.addCDPClient(.{
-        .socket = socket,
-        .ctx = client,
-        .blocking_read_start = Client.blockingReadStart,
-        .blocking_read = Client.blockingRead,
-        .blocking_read_end = Client.blockingReadStop,
-    });
-    defer http.removeCDPClient();
+    self.registerClient(client);
+    defer self.unregisterClient(client);
 
-    lp.assert(client.mode == .http, "Server.readLoop invalid mode", .{});
-    while (true) {
-        if (http.poll(timeout_ms) != .cdp_socket) {
-            log.info(.app, "CDP timeout", .{});
-            return;
-        }
+    client.start();
+}
 
-        if (client.readSocket() == false) {
-            return;
-        }
+fn getClient(self: *Server) !*Client {
+    self.clients_mu.lock();
+    defer self.clients_mu.unlock();
+    return self.clients_pool.create();
+}
 
-        if (client.mode == .cdp) {
-            break; // switch to our CDP loop
-        }
-    }
+fn releaseClient(self: *Server, client: *Client) void {
+    self.clients_mu.lock();
+    defer self.clients_mu.unlock();
+    self.clients_pool.destroy(client);
+}
 
-    var cdp = &client.mode.cdp;
-    var last_message = timestamp(.monotonic);
-    var ms_remaining = timeout_ms;
-    while (true) {
-        switch (cdp.pageWait(ms_remaining)) {
-            .cdp_socket => {
-                if (client.readSocket() == false) {
-                    return;
-                }
-                last_message = timestamp(.monotonic);
-                ms_remaining = timeout_ms;
-            },
-            .no_page => {
-                if (http.poll(ms_remaining) != .cdp_socket) {
-                    log.info(.app, "CDP timeout", .{});
-                    return;
-                }
-                if (client.readSocket() == false) {
-                    return;
-                }
-                last_message = timestamp(.monotonic);
-                ms_remaining = timeout_ms;
-            },
-            .done => {
-                const elapsed = timestamp(.monotonic) - last_message;
-                if (elapsed > ms_remaining) {
-                    log.info(.app, "CDP timeout", .{});
-                    return;
-                }
-                ms_remaining -= @intCast(elapsed);
-            },
-            .navigate => unreachable, // must have been handled by the session
+fn registerClient(self: *Server, client: *Client) void {
+    self.clients_mu.lock();
+    defer self.clients_mu.unlock();
+    self.clients.append(self.allocator, client) catch {};
+}
+
+fn unregisterClient(self: *Server, client: *Client) void {
+    self.clients_mu.lock();
+    defer self.clients_mu.unlock();
+    for (self.clients.items, 0..) |c, i| {
+        if (c == client) {
+            _ = self.clients.swapRemove(i);
+            break;
         }
     }
 }
 
+fn spawnWorker(self: *Server, socket: posix.socket_t, timeout_ms: u32) !void {
+    if (self.shutdown.load(.acquire)) {
+        return error.ShuttingDown;
+    }
+
+    if (self.active_threads.load(.monotonic) >= self.app.config.maxConnections()) {
+        return error.MaxThreadsReached;
+    }
+
+    _ = self.active_threads.fetchAdd(1, .monotonic);
+    errdefer _ = self.active_threads.fetchSub(1, .monotonic);
+
+    const thread = try std.Thread.spawn(.{}, runWorker, .{ self, socket, timeout_ms });
+    thread.detach();
+}
+
+fn runWorker(self: *Server, socket: posix.socket_t, timeout_ms: u32) void {
+    defer _ = self.active_threads.fetchSub(1, .monotonic);
+    handleConnection(self, socket, timeout_ms);
+}
+
+fn joinThreads(self: *Server) void {
+    while (self.active_threads.load(.monotonic) > 0) {
+        std.Thread.sleep(10 * std.time.ns_per_ms);
+    }
+}
+
+// Handle exactly one TCP connection.
 pub const Client = struct {
     // The client is initially serving HTTP requests but, under normal circumstances
     // should eventually be upgraded to a websocket connections
@@ -218,11 +233,15 @@ pub const Client = struct {
         cdp: CDP,
     },
 
-    server: *Server,
+    allocator: Allocator,
+    app: *App,
+    http: *HttpClient,
+    json_version_response: []const u8,
     reader: Reader(true),
     socket: posix.socket_t,
     socket_flags: usize,
     send_arena: ArenaAllocator,
+    timeout_ms: u32,
 
     const EMPTY_PONG = [_]u8{ 138, 0 };
 
@@ -233,22 +252,42 @@ pub const Client = struct {
     // "private-use" close codes must be from 4000-49999
     const CLOSE_TIMEOUT = [_]u8{ 136, 2, 15, 160 }; // code: 4000
 
-    fn init(socket: posix.socket_t, server: *Server) !Client {
+    fn init(
+        socket: posix.socket_t,
+        allocator: Allocator,
+        app: *App,
+        json_version_response: []const u8,
+        timeout_ms: u32,
+    ) !Client {
+        if (log.enabled(.app, .info)) {
+            var client_address: std.net.Address = undefined;
+            var socklen: posix.socklen_t = @sizeOf(net.Address);
+            try std.posix.getsockname(socket, &client_address.any, &socklen);
+            log.info(.app, "client connected", .{ .ip = client_address });
+        }
+
         const socket_flags = try posix.fcntl(socket, posix.F.GETFL, 0);
         const nonblocking = @as(u32, @bitCast(posix.O{ .NONBLOCK = true }));
         // we expect the socket to come to us as nonblocking
         lp.assert(socket_flags & nonblocking == nonblocking, "Client.init blocking", .{});
 
-        var reader = try Reader(true).init(server.allocator);
+        var reader = try Reader(true).init(allocator);
         errdefer reader.deinit();
 
+        const http = try app.http.createClient(allocator);
+        errdefer http.deinit();
+
         return .{
             .socket = socket,
-            .server = server,
+            .allocator = allocator,
+            .app = app,
+            .http = http,
+            .json_version_response = json_version_response,
             .reader = reader,
             .mode = .{ .http = {} },
             .socket_flags = socket_flags,
-            .send_arena = ArenaAllocator.init(server.allocator),
+            .send_arena = ArenaAllocator.init(allocator),
+            .timeout_ms = timeout_ms,
         };
     }
 
@@ -259,6 +298,93 @@ pub const Client = struct {
         }
         self.reader.deinit();
         self.send_arena.deinit();
+        self.http.deinit();
+    }
+
+    fn start(self: *Client) void {
+        const http = self.http;
+        http.cdp_client = .{
+            .socket = self.socket,
+            .ctx = self,
+            .blocking_read_start = Client.blockingReadStart,
+            .blocking_read = Client.blockingRead,
+            .blocking_read_end = Client.blockingReadStop,
+        };
+        defer http.cdp_client = null;
+
+        self.httpLoop(http) catch |err| {
+            log.err(.app, "CDP client loop", .{ .err = err });
+        };
+    }
+
+    fn stop(self: *Client) void {
+        posix.shutdown(self.socket, .recv) catch {};
+    }
+
+    fn httpLoop(self: *Client, http: *HttpClient) !void {
+        lp.assert(self.mode == .http, "Client.httpLoop invalid mode", .{});
+        while (true) {
+            const status = http.tick(self.timeout_ms) catch |err| {
+                log.err(.app, "http tick", .{ .err = err });
+                return;
+            };
+            if (status != .cdp_socket) {
+                log.info(.app, "CDP timeout", .{});
+                return;
+            }
+
+            if (self.readSocket() == false) {
+                return;
+            }
+
+            if (self.mode == .cdp) {
+                break;
+            }
+        }
+
+        return self.cdpLoop(http);
+    }
+
+    fn cdpLoop(self: *Client, http: *HttpClient) !void {
+        var cdp = &self.mode.cdp;
+        var last_message = timestamp(.monotonic);
+        var ms_remaining = self.timeout_ms;
+
+        while (true) {
+            switch (cdp.pageWait(ms_remaining)) {
+                .cdp_socket => {
+                    if (self.readSocket() == false) {
+                        return;
+                    }
+                    last_message = timestamp(.monotonic);
+                    ms_remaining = self.timeout_ms;
+                },
+                .no_page => {
+                    const status = http.tick(ms_remaining) catch |err| {
+                        log.err(.app, "http tick", .{ .err = err });
+                        return;
+                    };
+                    if (status != .cdp_socket) {
+                        log.info(.app, "CDP timeout", .{});
+                        return;
+                    }
+                    if (self.readSocket() == false) {
+                        return;
+                    }
+                    last_message = timestamp(.monotonic);
+                    ms_remaining = self.timeout_ms;
+                },
+                .done => {
+                    const elapsed = timestamp(.monotonic) - last_message;
+                    if (elapsed > ms_remaining) {
+                        log.info(.app, "CDP timeout", .{});
+                        return;
+                    }
+                    ms_remaining -= @intCast(elapsed);
+                },
+                .navigate => unreachable, // must have been handled by the session
+            }
+        }
     }
 
     fn blockingReadStart(ctx: *anyopaque) bool {
@@ -315,7 +441,7 @@ pub const Client = struct {
         lp.assert(self.reader.pos == 0, "Client.HTTP pos", .{ .pos = self.reader.pos });
         const request = self.reader.buf[0..self.reader.len];
 
-        if (request.len > MAX_HTTP_REQUEST_SIZE) {
+        if (request.len > Config.MAX_HTTP_REQUEST_SIZE) {
             self.writeHTTPErrorResponse(413, "Request too large");
             return error.RequestTooLarge;
         }
@@ -368,7 +494,7 @@ pub const Client = struct {
         }
 
         if (std.mem.eql(u8, url, "/json/version")) {
-            try self.send(self.server.json_version_response);
+            try self.send(self.json_version_response);
             // Chromedp (a Go driver) does an http request to /json/version
             // then to / (websocket upgrade) using a different connection.
             // Since we only allow 1 connection at a time, the 2nd one (the
@@ -473,7 +599,7 @@ pub const Client = struct {
             break :blk res;
         };
 
-        self.mode = .{ .cdp = try CDP.init(self.server.app, self) };
+        self.mode = .{ .cdp = try CDP.init(self.app, self.http, self) };
         return self.send(response);
     }
 
@@ -708,7 +834,7 @@ fn Reader(comptime EXPECT_MASK: bool) type {
                     if (message_len > 125) {
                         return error.ControlTooLarge;
                     }
-                } else if (message_len > MAX_MESSAGE_SIZE) {
+                } else if (message_len > Config.MAX_MESSAGE_SIZE) {
                     return error.TooLarge;
                 } else if (message_len > self.buf.len) {
                     const len = self.buf.len;
@@ -736,7 +862,7 @@ fn Reader(comptime EXPECT_MASK: bool) type {
 
                 if (is_continuation) {
                     const fragments = &(self.fragments orelse return error.InvalidContinuation);
-                    if (fragments.message.items.len + message_len > MAX_MESSAGE_SIZE) {
+                    if (fragments.message.items.len + message_len > Config.MAX_MESSAGE_SIZE) {
                         return error.TooLarge;
                     }
 
diff --git a/src/TestHTTPServer.zig b/src/TestHTTPServer.zig
index 19c5bbc9..d492f53f 100644
--- a/src/TestHTTPServer.zig
+++ b/src/TestHTTPServer.zig
@@ -56,9 +56,9 @@ pub fn run(self: *TestHTTPServer, wg: *std.Thread.WaitGroup) !void {
 
     wg.finish();
 
-    while (true) {
+    while (!self.shutdown.load(.acquire)) {
         const conn = listener.accept() catch |err| {
-            if (self.shutdown.load(.acquire) or err == error.SocketNotListening) {
+            if (err == error.SocketNotListening) {
                 return;
             }
             return err;
diff --git a/src/browser/Browser.zig b/src/browser/Browser.zig
index 54668987..5da04f24 100644
--- a/src/browser/Browser.zig
+++ b/src/browser/Browser.zig
@@ -24,9 +24,9 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 const js = @import("js/js.zig");
 const log = @import("../log.zig");
 const App = @import("../App.zig");
+const HttpClient = @import("../http/Client.zig");
 
 const ArenaPool = App.ArenaPool;
-const HttpClient = App.Http.Client;
 
 const IS_DEBUG = @import("builtin").mode == .Debug;
 
@@ -51,6 +51,7 @@ transfer_arena: ArenaAllocator,
 
 const InitOpts = struct {
     env: js.Env.InitOpts = .{},
+    http_client: *HttpClient,
 };
 
 pub fn init(app: *App, opts: InitOpts) !Browser {
@@ -65,7 +66,7 @@ pub fn init(app: *App, opts: InitOpts) !Browser {
         .session = null,
         .allocator = allocator,
         .arena_pool = &app.arena_pool,
-        .http_client = app.http.client,
+        .http_client = opts.http_client,
         .call_arena = ArenaAllocator.init(allocator),
         .page_arena = ArenaAllocator.init(allocator),
         .session_arena = ArenaAllocator.init(allocator),
diff --git a/src/browser/js/Env.zig b/src/browser/js/Env.zig
index 9001d343..110d43c1 100644
--- a/src/browser/js/Env.zig
+++ b/src/browser/js/Env.zig
@@ -37,6 +37,14 @@ const JsApis = bridge.JsApis;
 const Allocator = std.mem.Allocator;
 const IS_DEBUG = @import("builtin").mode == .Debug;
 
+fn initClassIds() void {
+    inline for (JsApis, 0..) |JsApi, i| {
+        JsApi.Meta.class_id = i;
+    }
+}
+
+var class_id_once = std.once(initClassIds);
+
 // The Env maps to a V8 isolate, which represents a isolated sandbox for
 // executing JavaScript. The Env is where we'll define our V8 <-> Zig bindings,
 // and it's where we'll start ExecutionWorlds, which actually execute JavaScript.
@@ -76,6 +84,9 @@ pub const InitOpts = struct {
 };
 
 pub fn init(app: *App, opts: InitOpts) !Env {
+    // Initialize class IDs once before any V8 work
+    class_id_once.call();
+
     const allocator = app.allocator;
     const snapshot = &app.snapshot;
 
@@ -117,8 +128,7 @@ pub fn init(app: *App, opts: InitOpts) !Env {
         temp_scope.init(isolate);
         defer temp_scope.deinit();
 
-        inline for (JsApis, 0..) |JsApi, i| {
-            JsApi.Meta.class_id = i;
+        inline for (JsApis, 0..) |_, i| {
             const data = v8.v8__Isolate__GetDataFromSnapshotOnce(isolate_handle, snapshot.data_start + i);
             const function_handle: *const v8.FunctionTemplate = @ptrCast(data);
             // Make function template eternal
diff --git a/src/browser/js/Inspector.zig b/src/browser/js/Inspector.zig
index 7ba97257..6fab9c91 100644
--- a/src/browser/js/Inspector.zig
+++ b/src/browser/js/Inspector.zig
@@ -38,11 +38,12 @@ const IS_DEBUG = @import("builtin").mode == .Debug;
 const Inspector = @This();
 
 unique_id: i64,
+allocator: Allocator,
 isolate: *v8.Isolate,
 handle: *v8.Inspector,
 client: *v8.InspectorClientImpl,
 default_context: ?v8.Global,
-session: ?Session,
+sessions: std.ArrayListUnmanaged(*Session),
 
 pub fn init(allocator: Allocator, isolate: *v8.Isolate) !*Inspector {
     const self = try allocator.create(Inspector);
@@ -50,7 +51,8 @@ pub fn init(allocator: Allocator, isolate: *v8.Isolate) !*Inspector {
 
     self.* = .{
         .unique_id = 1,
-        .session = null,
+        .allocator = allocator,
+        .sessions = .empty,
         .isolate = isolate,
         .client = undefined,
         .handle = undefined,
@@ -67,32 +69,43 @@ pub fn init(allocator: Allocator, isolate: *v8.Isolate) !*Inspector {
     return self;
 }
 
-pub fn deinit(self: *const Inspector, allocator: Allocator) void {
+pub fn deinit(self: *Inspector, allocator: Allocator) void {
     var hs: v8.HandleScope = undefined;
     v8.v8__HandleScope__CONSTRUCT(&hs, self.isolate);
     defer v8.v8__HandleScope__DESTRUCT(&hs);
 
-    if (self.session) |*s| {
-        s.deinit();
+    for (self.sessions.items) |session| {
+        session.deinit();
+        self.allocator.destroy(session);
     }
+    self.sessions.deinit(self.allocator);
+
     v8.v8_inspector__Client__IMPL__DELETE(self.client);
     v8.v8_inspector__Inspector__DELETE(self.handle);
     allocator.destroy(self);
 }
 
-pub fn startSession(self: *Inspector, ctx: anytype) *Session {
-    if (comptime IS_DEBUG) {
-        std.debug.assert(self.session == null);
-    }
+pub fn startSession(self: *Inspector, ctx: anytype) !*Session {
+    const session = try self.allocator.create(Session);
+    errdefer self.allocator.destroy(session);
 
-    self.session = @as(Session, undefined);
-    Session.init(&self.session.?, self, ctx);
-    return &self.session.?;
+    Session.init(session, self, ctx);
+    try self.sessions.append(self.allocator, session);
+    return session;
 }
 
-pub fn stopSession(self: *Inspector) void {
-    self.session.?.deinit();
-    self.session = null;
+pub fn stopSession(self: *Inspector, session: *Session) void {
+    for (self.sessions.items, 0..) |s, i| {
+        if (s == session) {
+            _ = self.sessions.swapRemove(i);
+            session.deinit();
+            self.allocator.destroy(session);
+            return;
+        }
+    }
+    if (comptime IS_DEBUG) {
+        @panic("Tried to stop unknown inspector session");
+    }
 }
 
 // From CDP docs
diff --git a/src/cdp/cdp.zig b/src/cdp/cdp.zig
index 99310255..bd0574b7 100644
--- a/src/cdp/cdp.zig
+++ b/src/cdp/cdp.zig
@@ -28,6 +28,7 @@ const js = @import("../browser/js/js.zig");
 const App = @import("../App.zig");
 const Browser = @import("../browser/Browser.zig");
 const Session = @import("../browser/Session.zig");
+const HttpClient = @import("../http/Client.zig");
 const Page = @import("../browser/Page.zig");
 const Incrementing = @import("../id.zig").Incrementing;
 const Notification = @import("../Notification.zig");
@@ -85,10 +86,11 @@ pub fn CDPT(comptime TypeProvider: type) type {
 
         const Self = @This();
 
-        pub fn init(app: *App, client: TypeProvider.Client) !Self {
+        pub fn init(app: *App, http_client: *HttpClient, client: TypeProvider.Client) !Self {
             const allocator = app.allocator;
             const browser = try Browser.init(app, .{
                 .env = .{ .with_inspector = true },
+                .http_client = http_client,
             });
             errdefer browser.deinit();
 
@@ -403,8 +405,9 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             const session = try cdp.browser.newSession(notification);
 
             const browser = &cdp.browser;
-            const inspector_session = browser.env.inspector.?.startSession(self);
-            errdefer browser.env.inspector.?.stopSession();
+            const inspector = browser.env.inspector.?;
+            const inspector_session = try inspector.startSession(self);
+            errdefer inspector.stopSession(inspector_session);
 
             var registry = Node.Registry.init(allocator);
             errdefer registry.deinit();
@@ -455,7 +458,7 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             // before deinit it.
             browser.env.inspector.?.resetContextGroup();
             browser.runMessageLoop();
-            browser.env.inspector.?.stopSession();
+            browser.env.inspector.?.stopSession(self.inspector_session);
 
             // abort all intercepted requests before closing the sesion/page
             // since some of these might callback into the page/scriptmanager
diff --git a/src/cdp/testing.zig b/src/cdp/testing.zig
index 4de1e59f..a0369d0e 100644
--- a/src/cdp/testing.zig
+++ b/src/cdp/testing.zig
@@ -85,7 +85,7 @@ const TestContext = struct {
             self.client = Client.init(self.arena.allocator());
             // Don't use the arena here. We want to detect leaks in CDP.
             // The arena is only for test-specific stuff
-            self.cdp_ = TestCDP.init(base.test_app, &self.client.?) catch unreachable;
+            self.cdp_ = TestCDP.init(base.test_app, base.test_http, &self.client.?) catch unreachable;
         }
         return &self.cdp_.?;
     }
diff --git a/src/http/Http.zig b/src/http/Http.zig
index 3d488f95..42255120 100644
--- a/src/http/Http.zig
+++ b/src/http/Http.zig
@@ -17,8 +17,6 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 const std = @import("std");
-const lp = @import("lightpanda");
-const Config = @import("../Config.zig");
 
 pub const c = @cImport({
     @cInclude("curl/curl.h");
@@ -28,6 +26,8 @@ pub const ENABLE_DEBUG = false;
 pub const Client = @import("Client.zig");
 pub const Transfer = Client.Transfer;
 
+const lp = @import("lightpanda");
+const Config = @import("../Config.zig");
 const log = @import("../log.zig");
 const errors = @import("errors.zig");
 
@@ -41,8 +41,8 @@ const ArenaAllocator = std.heap.ArenaAllocator;
 // once for all http connections is a win.
 const Http = @This();
 
+allocator: Allocator,
 config: *const Config,
-client: *Client,
 ca_blob: ?c.curl_blob,
 arena: ArenaAllocator,
 
@@ -59,40 +59,28 @@ pub fn init(allocator: Allocator, config: *const Config) !Http {
 
     var ca_blob: ?c.curl_blob = null;
     if (config.tlsVerifyHost()) {
-        ca_blob = try loadCerts(allocator, arena.allocator());
+        ca_blob = try loadCerts(allocator);
     }
 
-    var client = try Client.init(allocator, ca_blob, config);
-    errdefer client.deinit();
-
     return .{
         .arena = arena,
-        .client = client,
         .ca_blob = ca_blob,
+        .allocator = allocator,
         .config = config,
     };
 }
 
 pub fn deinit(self: *Http) void {
-    self.client.deinit();
+    if (self.ca_blob) |ca_blob| {
+        const data: [*]u8 = @ptrCast(ca_blob.data);
+        self.allocator.free(data[0..ca_blob.len]);
+    }
     c.curl_global_cleanup();
     self.arena.deinit();
 }
 
-pub fn poll(self: *Http, timeout_ms: u32) Client.PerformStatus {
-    return self.client.tick(timeout_ms) catch |err| {
-        log.err(.app, "http poll", .{ .err = err });
-        return .normal;
-    };
-}
-
-pub fn addCDPClient(self: *Http, cdp_client: Client.CDPClient) void {
-    lp.assert(self.client.cdp_client == null, "Http addCDPClient existing", .{});
-    self.client.cdp_client = cdp_client;
-}
-
-pub fn removeCDPClient(self: *Http) void {
-    self.client.cdp_client = null;
+pub fn createClient(self: *Http, allocator: Allocator) !*Client {
+    return Client.init(allocator, self.ca_blob, self.config);
 }
 
 pub fn newConnection(self: *Http) !Connection {
@@ -348,7 +336,7 @@ pub const Method = enum(u8) {
 // This whole rescan + decode is really just needed for MacOS. On Linux
 // bundle.rescan does find the .pem file(s) which could be in a few different
 // places, so it's still useful, just not efficient.
-fn loadCerts(allocator: Allocator, arena: Allocator) !c.curl_blob {
+fn loadCerts(allocator: Allocator) !c.curl_blob {
     var bundle: std.crypto.Certificate.Bundle = .{};
     try bundle.rescan(allocator);
     defer bundle.deinit(allocator);
@@ -371,8 +359,9 @@ fn loadCerts(allocator: Allocator, arena: Allocator) !c.curl_blob {
         (bundle.map.count() * 75) + // start / end per certificate + extra, just in case
         (encoded_size / 64) // newline per 64 characters
     ;
-    try arr.ensureTotalCapacity(arena, buffer_size);
-    var writer = arr.writer(arena);
+    try arr.ensureTotalCapacity(allocator, buffer_size);
+    errdefer arr.deinit(allocator);
+    var writer = arr.writer(allocator);
 
     var it = bundle.map.valueIterator();
     while (it.next()) |index| {
@@ -385,11 +374,16 @@ fn loadCerts(allocator: Allocator, arena: Allocator) !c.curl_blob {
     }
 
     // Final encoding should not be larger than our initial size estimate
-    lp.assert(buffer_size > arr.items.len, "Http loadCerts", .{ .estiate = buffer_size, .len = arr.items.len });
+    lp.assert(buffer_size > arr.items.len, "Http loadCerts", .{ .estimate = buffer_size, .len = arr.items.len });
+
+    // Allocate exactly the size needed and copy the data
+    const result = try allocator.dupe(u8, arr.items);
+    // Free the original oversized allocation
+    arr.deinit(allocator);
 
     return .{
-        .len = arr.items.len,
-        .data = arr.items.ptr,
+        .len = result.len,
+        .data = result.ptr,
         .flags = 0,
     };
 }
diff --git a/src/lightpanda.zig b/src/lightpanda.zig
index 59ac4dc9..12481465 100644
--- a/src/lightpanda.zig
+++ b/src/lightpanda.zig
@@ -38,9 +38,12 @@ pub const FetchOpts = struct {
     dump: dump.RootOpts,
     writer: ?*std.Io.Writer = null,
 };
-pub fn fetch(app: *App, url: [:0]const u8, opts: FetchOpts) !void {
-    var browser = try Browser.init(app, .{});
-    const notification = try Notification.init(app.allocator);
+pub fn fetch(allocator: std.mem.Allocator, app: *App, url: [:0]const u8, opts: FetchOpts) !void {
+    const http_client = try app.http.createClient(allocator);
+    defer http_client.deinit();
+
+    var browser = try Browser.init(app, .{ .http_client = http_client });
+    const notification = try Notification.init(allocator);
     defer notification.deinit();
     defer browser.deinit();
 
diff --git a/src/log.zig b/src/log.zig
index 9936cbb0..168867ed 100644
--- a/src/log.zig
+++ b/src/log.zig
@@ -49,7 +49,7 @@ const Opts = struct {
 
 pub var opts = Opts{};
 
-// synchronizes writes to the output
+// synchronizes access to _interceptor
 var out_lock: Thread.Mutex = .{};
 
 // synchronizes access to last_log
@@ -146,7 +146,14 @@ fn logTo(comptime scope: Scope, level: Level, comptime msg: []const u8, data: an
     }
     out.flush() catch return;
 
-    const interceptor = _interceptor orelse return;
+    // Copy the interceptor under lock, then release before doing I/O
+    const interceptor = blk: {
+        out_lock.lock();
+        defer out_lock.unlock();
+        break :blk _interceptor orelse return;
+    };
+
+    // I/O operations happen without holding the lock to minimize contention
     if (interceptor.writer(interceptor.ctx, scope, level)) |iwriter| {
         try logLogfmt(scope, level, msg, data, iwriter);
         try iwriter.flush();
@@ -368,10 +375,14 @@ fn timestamp(comptime mode: datetime.TimestampMode) u64 {
 
 var _interceptor: ?Interceptor = null;
 pub fn registerInterceptor(interceptor: Interceptor) void {
+    out_lock.lock();
+    defer out_lock.unlock();
     _interceptor = interceptor;
 }
 
 pub fn unregisterInterceptor() void {
+    out_lock.lock();
+    defer out_lock.unlock();
     _interceptor = null;
 }
 
diff --git a/src/main.zig b/src/main.zig
index 76c23d74..e7aa184f 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -93,7 +93,7 @@ fn run(allocator: Allocator, main_arena: Allocator, sighandler: *SigHandler) !vo
             };
 
             // _server is global to handle graceful shutdown.
-            var server = try lp.Server.init(app, address);
+            var server = try lp.Server.init(allocator, app, address);
             defer server.deinit();
 
             try sighandler.on(lp.Server.stop, .{&server});
@@ -123,7 +123,7 @@ fn run(allocator: Allocator, main_arena: Allocator, sighandler: *SigHandler) !vo
                 fetch_opts.writer = &writer.interface;
             }
 
-            lp.fetch(app, url, fetch_opts) catch |err| {
+            lp.fetch(allocator, app, url, fetch_opts) catch |err| {
                 log.fatal(.app, "fetch error", .{ .err = err, .url = url });
                 return err;
             };
diff --git a/src/main_legacy_test.zig b/src/main_legacy_test.zig
index bc59492a..d8011120 100644
--- a/src/main_legacy_test.zig
+++ b/src/main_legacy_test.zig
@@ -44,8 +44,11 @@ pub fn main() !void {
     var test_arena = std.heap.ArenaAllocator.init(allocator);
     defer test_arena.deinit();
 
-    var browser = try lp.Browser.init(app, .{});
-    const notification = try lp.Notification.init(app.allocator);
+    const http_client = try app.http.createClient(allocator);
+    defer http_client.deinit();
+
+    var browser = try lp.Browser.init(app, .{ .http_client = http_client });
+    const notification = try lp.Notification.init(allocator);
     defer notification.deinit();
     defer browser.deinit();
 
diff --git a/src/main_wpt.zig b/src/main_wpt.zig
index 8647df96..562c57ea 100644
--- a/src/main_wpt.zig
+++ b/src/main_wpt.zig
@@ -67,7 +67,10 @@ pub fn main() !void {
     var app = try lp.App.init(allocator, &config);
     defer app.deinit();
 
-    var browser = try lp.Browser.init(app, .{});
+    const http_client = try app.http.createClient(allocator);
+    defer http_client.deinit();
+
+    var browser = try lp.Browser.init(app, .{ .http_client = http_client });
     defer browser.deinit();
 
     // An arena for running each tests. Is reset after every test.
@@ -109,7 +112,7 @@ fn run(
     test_file: []const u8,
     err_out: *?[]const u8,
 ) ![]const u8 {
-    const notification = try lp.Notification.init(browser.allocator);
+    const notification = try lp.Notification.init(browser.app.allocator);
     defer notification.deinit();
 
     const session = try browser.newSession(notification);
diff --git a/src/testing.zig b/src/testing.zig
index 41f67e96..c6af35d6 100644
--- a/src/testing.zig
+++ b/src/testing.zig
@@ -39,6 +39,7 @@ pub fn reset() void {
 const App = @import("App.zig");
 const js = @import("browser/js/js.zig");
 const Config = @import("Config.zig");
+const Client = @import("http/Client.zig");
 const Page = @import("browser/Page.zig");
 const Browser = @import("browser/Browser.zig");
 const Session = @import("browser/Session.zig");
@@ -334,6 +335,7 @@ fn isJsonValue(a: std.json.Value, b: std.json.Value) bool {
 }
 
 pub var test_app: *App = undefined;
+pub var test_http: *Client = undefined;
 pub var test_browser: Browser = undefined;
 pub var test_notification: *Notification = undefined;
 pub var test_session: *Session = undefined;
@@ -472,7 +474,10 @@ test "tests:beforeAll" {
     test_app = try App.init(test_allocator, &test_config);
     errdefer test_app.deinit();
 
-    test_browser = try Browser.init(test_app, .{});
+    test_http = try test_app.http.createClient(test_allocator);
+    errdefer test_http.deinit();
+
+    test_browser = try Browser.init(test_app, .{ .http_client = test_http });
     errdefer test_browser.deinit();
 
     // Create notification for testing
@@ -519,13 +524,15 @@ test "tests:afterAll" {
 
     test_notification.deinit();
     test_browser.deinit();
+    test_http.deinit();
     test_app.deinit();
     test_config.deinit(@import("root").tracking_allocator);
 }
 
 fn serveCDP(wg: *std.Thread.WaitGroup) !void {
     const address = try std.net.Address.parseIp("127.0.0.1", 9583);
-    test_cdp_server = try Server.init(test_app, address);
+    const test_allocator = @import("root").tracking_allocator;
+    test_cdp_server = try Server.init(test_allocator, test_app, address);
 
     wg.finish();