diff --git a/web/tests/lib/index.cjs b/web/tests/lib/index.cjs
index 3cb5747dae..a3df553e6f 100644
--- a/web/tests/lib/index.cjs
+++ b/web/tests/lib/index.cjs
@@ -42,11 +42,6 @@ require("@babel/register")({
     root: path.resolve(__dirname, "../.."),
 });
 
-// Create a helper function to avoid sneaky delays in tests.
-function immediate(f) {
-    return () => f();
-}
-
 // Find the files we need to run.
 const files = process.argv.slice(2);
 assert.notEqual(files.length, 0, "No tests found");
@@ -109,8 +104,6 @@ process.exitCode = 1;
         window.location.href = "http://zulip.zulipdev.com/#";
         namespace.set_global("localStorage", localStorage);
         ls_container.clear();
-        _.throttle = immediate;
-        _.debounce = immediate;
         zpage_billing_params.reset();
         zpage_params.reset();
 
diff --git a/web/tests/message_flags.test.cjs b/web/tests/message_flags.test.cjs
index b855a5f6e0..f67346fe20 100644
--- a/web/tests/message_flags.test.cjs
+++ b/web/tests/message_flags.test.cjs
@@ -2,7 +2,7 @@
 
 const assert = require("node:assert/strict");
 
-const {mock_esm, set_global, with_overrides, zrequire} = require("./lib/namespace.cjs");
+const {clock, mock_esm, set_global, with_overrides, zrequire} = require("./lib/namespace.cjs");
 const {run_test} = require("./lib/test.cjs");
 
 const channel = mock_esm("../src/channel");
@@ -193,6 +193,7 @@ run_test("read", ({override}) => {
         messages: [1, 2, 3, 4, 5],
     };
     channel_post_opts.success(success_response_data);
+    clock.runAll();
     assert.deepEqual(channel_post_opts, {
         url: "/json/messages/flags",
         data: {
@@ -231,31 +232,17 @@ run_test("read", ({override}) => {
     });
 
     // Messages still not acked yet
-    const events = {};
-    const stub_delay = 100;
-    function set_timeout(f, delay) {
-        assert.equal(delay, stub_delay);
-        events.f = f;
-        events.timer_set = true;
-        return;
-    }
-    set_global("setTimeout", set_timeout);
     // Mock successful flagging of ids
     success_response_data = {
         messages: [3, 4, 5, 6, 7],
     };
     channel_post_opts.success(success_response_data);
-    assert.ok(events.timer_set);
+    clock.tick(1100);
 
     // Mark them non-local
     local_msg_1.locally_echoed = false;
     local_msg_2.locally_echoed = false;
-
-    // Mock successful flagging of ids
-    success_response_data = {
-        messages: [3, 4, 5, 6, 7],
-    };
-    channel_post_opts.success(success_response_data);
+    clock.runAll();
 
     // Former locally echoed messages flagging retried
     assert.deepEqual(channel_post_opts, {
@@ -278,6 +265,8 @@ run_test("read", ({override}) => {
             flag: "read",
         },
     });
+
+    clock.reset();
 });
 
 run_test("read_empty_data", ({override}) => {
diff --git a/web/tests/user_search.test.cjs b/web/tests/user_search.test.cjs
index 088d966b71..262db80a8f 100644
--- a/web/tests/user_search.test.cjs
+++ b/web/tests/user_search.test.cjs
@@ -6,7 +6,7 @@ const {make_realm} = require("./lib/example_realm.cjs");
 const {make_user} = require("./lib/example_user.cjs");
 const {make_message_list} = require("./lib/message_list.cjs");
 const {mock_channel_get} = require("./lib/mock_channel.cjs");
-const {set_global, mock_esm, zrequire} = require("./lib/namespace.cjs");
+const {clock, mock_esm, zrequire} = require("./lib/namespace.cjs");
 const {run_test, noop} = require("./lib/test.cjs");
 const $ = require("./lib/zjquery.cjs");
 
@@ -30,12 +30,6 @@ mock_esm("../src/buddy_list", {
     buddy_list: fake_buddy_list,
 });
 
-function mock_setTimeout() {
-    set_global("setTimeout", (func) => {
-        func();
-    });
-}
-
 const popovers = mock_esm("../src/popovers");
 const presence = mock_esm("../src/presence");
 const sidebar_ui = mock_esm("../src/sidebar_ui");
@@ -93,6 +87,7 @@ function test(label, f) {
 function set_input_val(val) {
     $("input.user-list-filter").val(val);
     $("input.user-list-filter").trigger("input");
+    clock.runAll();
 }
 
 function stub_buddy_list_empty_list_message_lengths() {
@@ -199,7 +194,6 @@ test("fetch on search", async ({override}) => {
 test("blur search right", ({override}) => {
     override(sidebar_ui, "show_userlist_sidebar", noop);
     override(popovers, "hide_all", noop);
-    mock_setTimeout();
 
     $("input.user-list-filter").closest = (selector) => {
         assert.equal(selector, ".app-main [class^='column-']");
@@ -209,13 +203,13 @@ test("blur search right", ({override}) => {
     $("input.user-list-filter").trigger("blur");
     assert.equal($("input.user-list-filter").is_focused(), false);
     activity_ui.initiate_search();
+    clock.runAll();
     assert.equal($("input.user-list-filter").is_focused(), true);
 });
 
 test("blur search left", ({override}) => {
     override(sidebar_ui, "show_streamlist_sidebar", noop);
     override(popovers, "hide_all", noop);
-    mock_setTimeout();
 
     $("input.user-list-filter").closest = (selector) => {
         assert.equal(selector, ".app-main [class^='column-']");
@@ -225,6 +219,7 @@ test("blur search left", ({override}) => {
     $("input.user-list-filter").trigger("blur");
     assert.equal($("input.user-list-filter").is_focused(), false);
     activity_ui.initiate_search();
+    clock.runAll();
     assert.equal($("input.user-list-filter").is_focused(), true);
 });