2 files changed, 61 insertions, 7 deletions

diff --git a/ext/web/15_performance.js b/ext/web/15_performance.js
index 5045c0d31..ea5557278 100644
--- a/ext/web/15_performance.js
+++ b/ext/web/15_performance.js
@@ -3,10 +3,7 @@
 import { primordials } from "ext:core/mod.js";
 const {
   ArrayPrototypeFilter,
-  ArrayPrototypeFind,
   ArrayPrototypePush,
-  ArrayPrototypeReverse,
-  ArrayPrototypeSlice,
   ObjectKeys,
   ObjectPrototypeIsPrototypeOf,
   ReflectHas,
@@ -101,10 +98,12 @@ function findMostRecent(
   name,
   type,
 ) {
-  return ArrayPrototypeFind(
-    ArrayPrototypeReverse(ArrayPrototypeSlice(performanceEntries)),
-    (entry) => entry.name === name && entry.entryType === type,
-  );
+  for (let i = performanceEntries.length - 1; i >= 0; --i) {
+    const entry = performanceEntries[i];
+    if (entry.name === name && entry.entryType === type) {
+      return entry;
+    }
+  }
 }
 
 function convertMarkToTimestamp(mark) {
diff --git a/tests/unit/performance_test.ts b/tests/unit/performance_test.ts
index 93af641ad..fa056c7f5 100644
--- a/tests/unit/performance_test.ts
+++ b/tests/unit/performance_test.ts
@@ -2,6 +2,7 @@
 import {
   assert,
   assertEquals,
+  assertNotEquals,
   assertNotStrictEquals,
   assertStringIncludes,
   assertThrows,
@@ -36,6 +37,41 @@ Deno.test(function performanceToJSON() {
   assertEquals(Object.keys(json).length, 1);
 });
 
+Deno.test(function clearMarks() {
+  performance.mark("a");
+  performance.mark("a");
+  performance.mark("b");
+  performance.mark("c");
+
+  const marksNum = performance.getEntriesByType("mark").length;
+
+  performance.clearMarks("a");
+  assertEquals(performance.getEntriesByType("mark").length, marksNum - 2);
+
+  performance.clearMarks();
+  assertEquals(performance.getEntriesByType("mark").length, 0);
+});
+
+Deno.test(function clearMeasures() {
+  performance.measure("from-start");
+  performance.mark("a");
+  performance.measure("from-mark-a", "a");
+  performance.measure("from-start");
+  performance.measure("from-mark-a", "a");
+  performance.mark("b");
+  performance.measure("between-a-and-b", "a", "b");
+
+  const measuresNum = performance.getEntriesByType("measure").length;
+
+  performance.clearMeasures("from-start");
+  assertEquals(performance.getEntriesByType("measure").length, measuresNum - 2);
+
+  performance.clearMeasures();
+  assertEquals(performance.getEntriesByType("measure").length, 0);
+
+  performance.clearMarks();
+});
+
 Deno.test(function performanceMark() {
   const mark = performance.mark("test");
   assert(mark instanceof PerformanceMark);
@@ -127,6 +163,25 @@ Deno.test(function performanceMeasure() {
   });
 });
 
+Deno.test(function performanceMeasureUseMostRecentMark() {
+  const markName1 = "mark1";
+  const measureName1 = "measure1";
+  const mark1 = performance.mark(markName1);
+  return new Promise((resolve, reject) => {
+    setTimeout(() => {
+      try {
+        const laterMark1 = performance.mark(markName1);
+        const measure1 = performance.measure(measureName1, markName1);
+        assertNotEquals(mark1.startTime, measure1.startTime);
+        assertEquals(laterMark1.startTime, measure1.startTime);
+      } catch (e) {
+        return reject(e);
+      }
+      resolve();
+    }, 100);
+  });
+});
+
 Deno.test(function performanceCustomInspectFunction() {
   assertStringIncludes(Deno.inspect(performance), "Performance");
   assertStringIncludes(