diff --git a/packages/scheduler/src/Scheduler.js b/packages/scheduler/src/Scheduler.js
index 952dd19cc839a..0536e8de77b32 100644
--- a/packages/scheduler/src/Scheduler.js
+++ b/packages/scheduler/src/Scheduler.js
@@ -13,9 +13,8 @@ import {
   enableProfiling,
 } from './SchedulerFeatureFlags';
 import {
-  requestHostCallback as requestHostCallbackWithoutProfiling,
+  requestHostCallback,
   requestHostTimeout,
-  cancelHostCallback,
   cancelHostTimeout,
   shouldYieldToHost,
   getCurrentTime,
@@ -79,17 +78,6 @@ var isPerformingWork = false;
 var isHostCallbackScheduled = false;
 var isHostTimeoutScheduled = false;
 
-function requestHostCallbackWithProfiling(cb, time) {
-  if (enableProfiling) {
-    markSchedulerSuspended(time);
-    requestHostCallbackWithoutProfiling(cb);
-  }
-}
-
-const requestHostCallback = enableProfiling
-  ? requestHostCallbackWithProfiling
-  : requestHostCallbackWithoutProfiling;
-
 function advanceTimers(currentTime) {
   // Check for tasks that are no longer delayed and add them to the queue.
   let timer = peek(timerQueue);
@@ -121,7 +109,7 @@ function handleTimeout(currentTime) {
   if (!isHostCallbackScheduled) {
     if (peek(taskQueue) !== null) {
       isHostCallbackScheduled = true;
-      requestHostCallback(flushWork, currentTime);
+      requestHostCallback(flushWork);
     } else {
       const firstTimer = peek(timerQueue);
       if (firstTimer !== null) {
@@ -132,7 +120,7 @@ function handleTimeout(currentTime) {
 }
 
 function flushWork(hasTimeRemaining, initialTime) {
-  if (isHostCallbackScheduled) {
+  if (enableProfiling) {
     markSchedulerUnsuspended(initialTime);
   }
 
@@ -190,8 +178,6 @@ function flushWork(hasTimeRemaining, initialTime) {
     }
     // Return whether there's additional work
     if (currentTask !== null) {
-      markSchedulerSuspended(currentTime);
-      isHostCallbackScheduled = true;
       return true;
     } else {
       let firstTimer = peek(timerQueue);
@@ -213,6 +199,10 @@ function flushWork(hasTimeRemaining, initialTime) {
     currentTask = null;
     currentPriorityLevel = previousPriorityLevel;
     isPerformingWork = false;
+    if (enableProfiling) {
+      const currentTime = getCurrentTime();
+      markSchedulerSuspended(currentTime);
+    }
   }
 }
 
@@ -378,7 +368,7 @@ function unstable_scheduleCallback(priorityLevel, callback, options) {
     // wait until the next time we yield.
     if (!isHostCallbackScheduled && !isPerformingWork) {
       isHostCallbackScheduled = true;
-      requestHostCallback(flushWork, currentTime);
+      requestHostCallback(flushWork);
     }
   }
 
@@ -393,12 +383,7 @@ function unstable_continueExecution() {
   isSchedulerPaused = false;
   if (!isHostCallbackScheduled && !isPerformingWork) {
     isHostCallbackScheduled = true;
-    if (enableProfiling) {
-      const currentTime = getCurrentTime();
-      requestHostCallbackWithProfiling(flushWork, currentTime);
-    } else {
-      requestHostCallback(flushWork);
-    }
+    requestHostCallback(flushWork);
   }
 }
 
@@ -407,10 +392,12 @@ function unstable_getFirstCallbackNode() {
 }
 
 function unstable_cancelCallback(task) {
-  if (enableProfiling && task.isQueued) {
-    const currentTime = getCurrentTime();
-    markTaskCanceled(task, currentTime);
-    task.isQueued = false;
+  if (enableProfiling) {
+    if (task.isQueued) {
+      const currentTime = getCurrentTime();
+      markTaskCanceled(task, currentTime);
+      task.isQueued = false;
+    }
   }
 
   // Null out the callback to indicate the task has been canceled. (Can't
diff --git a/packages/scheduler/src/__tests__/SchedulerProfiling-test.js b/packages/scheduler/src/__tests__/SchedulerProfiling-test.js
index a352ea982fd72..9e44215a819d1 100644
--- a/packages/scheduler/src/__tests__/SchedulerProfiling-test.js
+++ b/packages/scheduler/src/__tests__/SchedulerProfiling-test.js
@@ -217,10 +217,10 @@ describe('Scheduler', () => {
 
     const mainThreadLabelColumn = '!!! Main thread              ';
     let mainThreadTimelineColumn = '';
-    let isMainThreadBusy = false;
+    let isMainThreadBusy = true;
     for (const time of mainThreadRuns) {
       const index = time / msPerChar;
-      mainThreadTimelineColumn += (isMainThreadBusy ? '█' : ' ').repeat(
+      mainThreadTimelineColumn += (isMainThreadBusy ? '█' : '░').repeat(
         index - mainThreadTimelineColumn.length,
       );
       isMainThreadBusy = !isMainThreadBusy;
@@ -325,7 +325,7 @@ describe('Scheduler', () => {
 
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │          ██
+!!! Main thread              │██░░░░░░░░██░░░░░░░░░░░░
 Task 2 [User-blocking]       │        ░░░░██████
 Task 1 [Normal]              │  ████████░░░░░░░░██████
 `,
@@ -353,15 +353,11 @@ Task 1 [Normal]              │  ████████░░░░░░░
 
     cancelCallback(task);
 
-    // Advance more time. This should not affect the size of the main
-    // thread row, since the Scheduler queue is empty.
     Scheduler.unstable_advanceTime(1000);
     expect(Scheduler).toFlushWithoutYielding();
-
-    // The main thread row should end when the callback is cancelled.
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │      ██
+!!! Main thread              │░░░░░░██████████████████████
 Task 1 [Normal]              │██████░░🡐 canceled
 `,
     );
@@ -378,15 +374,11 @@ Task 1 [Normal]              │██████░░🡐 canceled
     expect(Scheduler).toFlushAndThrow('Oops');
     Scheduler.unstable_advanceTime(100);
 
-    // Advance more time. This should not affect the size of the main
-    // thread row, since the Scheduler queue is empty.
     Scheduler.unstable_advanceTime(1000);
     expect(Scheduler).toFlushWithoutYielding();
-
-    // The main thread row should end when the callback is cancelled.
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │
+!!! Main thread              │░░░░░░██████████████████████
 Task 1 [Normal]              │██████🡐 errored
 `,
     );
@@ -431,7 +423,7 @@ Task 1 [Normal]              │██████🡐 errored
     // The main thread row should end when the callback is cancelled.
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │      ██
+!!! Main thread              │░░░░░░██████████████████████
 Task 1 [Normal]              │██████░░🡐 canceled
 Task 2 [Normal]              │░░░░░░░░🡐 canceled
 `,
@@ -449,7 +441,7 @@ Task 2 [Normal]              │░░░░░░░░🡐 canceled
     cancelCallback(task);
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │
+!!! Main thread              │░░░░░░░░░░░░░░░░░░░░
 Task 1 [Normal]              │████████████████████
 `,
     );
@@ -482,7 +474,7 @@ Task 1 [Normal]              │████████████████
     expect(Scheduler).toFlushAndYield(['A']);
     expect(stopProfilingAndPrintFlamegraph()).toEqual(
       `
-!!! Main thread              │████████████
+!!! Main thread              │████████████░░░░░░░░░░░░░░░░░░░░
 Task 1 [Normal]              │░░░░░░░░░░░░████████████████████
 Task 2 [Normal]              │    ░░░░░░░░🡐 canceled
 `,