From 71707b5aa702aa9b1ce08ebd8bc7564c3e7da0cb Mon Sep 17 00:00:00 2001
From: Pierre Tachoire <pierre@lightpanda.io>
Date: Tue, 24 Feb 2026 09:12:18 +0100
Subject: [PATCH 1/2] accept more performance mark name and return dummy 0

---
 src/browser/tests/performance.html | 22 +++++++++++++++++
 src/browser/webapi/Performance.zig | 38 ++++++++++++++++++++++++++----
 2 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/src/browser/tests/performance.html b/src/browser/tests/performance.html
index 5928bba9..01d23ab4 100644
--- a/src/browser/tests/performance.html
+++ b/src/browser/tests/performance.html
@@ -252,6 +252,28 @@
   }
 </script>
 
+<script id=measure_with_navigation_timing_marks>
+  {
+    // performance.measure() must accept PerformanceTiming attribute names
+    // (e.g. "fetchStart") as start/end marks per the W3C User Timing Level 2 spec.
+    // https://www.w3.org/TR/user-timing/#dom-performance-measure
+    performance.clearMarks();
+    performance.clearMeasures();
+
+    performance.mark("mark-dataComplete");
+    let m = performance.measure("dataComplete", "fetchStart", "mark-dataComplete");
+    testing.expectEqual('dataComplete', m.name);
+    testing.expectEqual('measure', m.entryType);
+    testing.expectEqual(true, m.duration >= 0);
+
+    // navigationStart is also a valid mark name (was already supported)
+    performance.mark("mark-end");
+    let m2 = performance.measure("fromNav", "navigationStart", "mark-end");
+    testing.expectEqual('fromNav', m2.name);
+    testing.expectEqual(true, m2.duration >= 0);
+  }
+</script>
+
 <script id=mixed_marks_and_measures>
   {
     performance.clearMarks();
diff --git a/src/browser/webapi/Performance.zig b/src/browser/webapi/Performance.zig
index fef02036..052a6ca3 100644
--- a/src/browser/webapi/Performance.zig
+++ b/src/browser/webapi/Performance.zig
@@ -208,10 +208,40 @@ fn getMarkTime(self: *const Performance, mark_name: []const u8) !f64 {
         }
     }
 
-    // Recognized mark names by browsers. `navigationStart` is an equivalent
-    // to 0. Others are dependant to request arrival, end of request etc.
-    if (std.mem.eql(u8, "navigationStart", mark_name)) {
-        return 0;
+    // PerformanceTiming attribute names are valid start/end marks per the
+    // W3C User Timing Level 2 spec. All are relative to navigationStart (= 0).
+    // https://www.w3.org/TR/user-timing/#dom-performance-measure
+    //
+    // `navigationStart` is an equivalent to 0.
+    // Others are dependant to request arrival, end of request etc, but we
+    // return a dummy 0 value for now.
+    const navigation_timing_marks = [_][]const u8{
+        "navigationStart",
+        "unloadEventStart",
+        "unloadEventEnd",
+        "redirectStart",
+        "redirectEnd",
+        "fetchStart",
+        "domainLookupStart",
+        "domainLookupEnd",
+        "connectStart",
+        "connectEnd",
+        "secureConnectionStart",
+        "requestStart",
+        "responseStart",
+        "responseEnd",
+        "domLoading",
+        "domInteractive",
+        "domContentLoadedEventStart",
+        "domContentLoadedEventEnd",
+        "domComplete",
+        "loadEventStart",
+        "loadEventEnd",
+    };
+    for (navigation_timing_marks) |name| {
+        if (std.mem.eql(u8, name, mark_name)) {
+            return 0;
+        }
     }
 
     return error.SyntaxError; // Mark not found

From 42df54869fc77797f5ca01a74474e7dd258ad3fa Mon Sep 17 00:00:00 2001
From: Pierre Tachoire <pierre@lightpanda.io>
Date: Tue, 24 Feb 2026 15:18:25 +0100
Subject: [PATCH 2/2] performance: use a comptime StaticStringMap for string
 comparison

---
 src/browser/webapi/Performance.zig | 52 ++++++++++++++----------------
 1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/src/browser/webapi/Performance.zig b/src/browser/webapi/Performance.zig
index 052a6ca3..78070893 100644
--- a/src/browser/webapi/Performance.zig
+++ b/src/browser/webapi/Performance.zig
@@ -215,33 +215,31 @@ fn getMarkTime(self: *const Performance, mark_name: []const u8) !f64 {
     // `navigationStart` is an equivalent to 0.
     // Others are dependant to request arrival, end of request etc, but we
     // return a dummy 0 value for now.
-    const navigation_timing_marks = [_][]const u8{
-        "navigationStart",
-        "unloadEventStart",
-        "unloadEventEnd",
-        "redirectStart",
-        "redirectEnd",
-        "fetchStart",
-        "domainLookupStart",
-        "domainLookupEnd",
-        "connectStart",
-        "connectEnd",
-        "secureConnectionStart",
-        "requestStart",
-        "responseStart",
-        "responseEnd",
-        "domLoading",
-        "domInteractive",
-        "domContentLoadedEventStart",
-        "domContentLoadedEventEnd",
-        "domComplete",
-        "loadEventStart",
-        "loadEventEnd",
-    };
-    for (navigation_timing_marks) |name| {
-        if (std.mem.eql(u8, name, mark_name)) {
-            return 0;
-        }
+    const navigation_timing_marks = std.StaticStringMap(void).initComptime(.{
+        .{ "navigationStart", {} },
+        .{ "unloadEventStart", {} },
+        .{ "unloadEventEnd", {} },
+        .{ "redirectStart", {} },
+        .{ "redirectEnd", {} },
+        .{ "fetchStart", {} },
+        .{ "domainLookupStart", {} },
+        .{ "domainLookupEnd", {} },
+        .{ "connectStart", {} },
+        .{ "connectEnd", {} },
+        .{ "secureConnectionStart", {} },
+        .{ "requestStart", {} },
+        .{ "responseStart", {} },
+        .{ "responseEnd", {} },
+        .{ "domLoading", {} },
+        .{ "domInteractive", {} },
+        .{ "domContentLoadedEventStart", {} },
+        .{ "domContentLoadedEventEnd", {} },
+        .{ "domComplete", {} },
+        .{ "loadEventStart", {} },
+        .{ "loadEventEnd", {} },
+    });
+    if (navigation_timing_marks.has(mark_name)) {
+        return 0;
     }
 
     return error.SyntaxError; // Mark not found