diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index fc03fb25bd06..e948dec5a4da 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -1683,7 +1683,7 @@ void nsJSContext::EnsureCCRunner(TimeDuration aDelay, TimeDuration aBudget) {
         CCRunnerFired, "EnsureCCRunner::CCRunnerFired", aDelay.ToMilliseconds(),
         aBudget.ToMilliseconds(), true, [] { return sShuttingDown; });
   } else {
-    sCCRunner->SetBudget(aBudget.ToMilliseconds());
+    sCCRunner->SetMinimumUsefulBudget(aBudget.ToMilliseconds());
     nsIEventTarget* target = mozilla::GetCurrentEventTarget();
     if (target) {
       sCCRunner->SetTimer(aDelay.ToMilliseconds(), target);
diff --git a/xpcom/threads/IdleTaskRunner.cpp b/xpcom/threads/IdleTaskRunner.cpp
index 404410bec867..792f1d9285ab 100644
--- a/xpcom/threads/IdleTaskRunner.cpp
+++ b/xpcom/threads/IdleTaskRunner.cpp
@@ -12,27 +12,28 @@ namespace mozilla {
 
 already_AddRefed<IdleTaskRunner> IdleTaskRunner::Create(
     const CallbackType& aCallback, const char* aRunnableName,
-    uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
+    uint32_t aMaxDelay, int64_t aMinimumUsefulBudget, bool aRepeating,
     const MayStopProcessingCallbackType& aMayStopProcessing) {
   if (aMayStopProcessing && aMayStopProcessing()) {
     return nullptr;
   }
 
   RefPtr<IdleTaskRunner> runner =
-      new IdleTaskRunner(aCallback, aRunnableName, aMaxDelay, aNonIdleBudget,
-                         aRepeating, aMayStopProcessing);
+      new IdleTaskRunner(aCallback, aRunnableName, aMaxDelay,
+                         aMinimumUsefulBudget, aRepeating, aMayStopProcessing);
   runner->Schedule(false);  // Initial scheduling shouldn't use idle dispatch.
   return runner.forget();
 }
 
 IdleTaskRunner::IdleTaskRunner(
     const CallbackType& aCallback, const char* aRunnableName,
-    uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
+    uint32_t aMaxDelay, int64_t aMinimumUsefulBudget, bool aRepeating,
     const MayStopProcessingCallbackType& aMayStopProcessing)
     : CancelableIdleRunnable(aRunnableName),
       mCallback(aCallback),
       mDelay(aMaxDelay),
-      mBudget(TimeDuration::FromMilliseconds(aNonIdleBudget)),
+      mMinimumUsefulBudget(
+          TimeDuration::FromMilliseconds(aMinimumUsefulBudget)),
       mRepeating(aRepeating),
       mTimerActive(false),
       mMayStopProcessing(aMayStopProcessing),
@@ -49,7 +50,7 @@ IdleTaskRunner::Run() {
   bool deadLineWasNull = mDeadline.IsNull();
   bool didRun = false;
   bool allowIdleDispatch = false;
-  if (deadLineWasNull || ((now + mBudget) < mDeadline)) {
+  if (deadLineWasNull || ((now + mMinimumUsefulBudget) < mDeadline)) {
     CancelTimer();
     didRun = mCallback(mDeadline);
     // If we didn't do meaningful work, don't schedule using immediate
@@ -78,8 +79,8 @@ void IdleTaskRunner::SetDeadline(mozilla::TimeStamp aDeadline) {
   mDeadline = aDeadline;
 }
 
-void IdleTaskRunner::SetBudget(int64_t aBudget) {
-  mBudget = TimeDuration::FromMilliseconds(aBudget);
+void IdleTaskRunner::SetMinimumUsefulBudget(int64_t aMinimumUsefulBudget) {
+  mMinimumUsefulBudget = TimeDuration::FromMilliseconds(aMinimumUsefulBudget);
 }
 
 void IdleTaskRunner::SetTimer(uint32_t aDelay, nsIEventTarget* aTarget) {
diff --git a/xpcom/threads/IdleTaskRunner.h b/xpcom/threads/IdleTaskRunner.h
index 93a55b3d7f4c..6d1af26b050d 100644
--- a/xpcom/threads/IdleTaskRunner.h
+++ b/xpcom/threads/IdleTaskRunner.h
@@ -29,13 +29,12 @@ class IdleTaskRunner final : public CancelableIdleRunnable {
   using MayStopProcessingCallbackType = std::function<bool()>;
 
  public:
-  // An IdleTaskRunner will attempt to run in idle time, with a budget computed
-  // based on a (capped) estimate for how much idle time is available. If there
-  // is no idle time within `aMaxDelay` ms, it will fall back to running using
-  // a specified `aNonIdleBudget`.
+  // An IdleTaskRunner will attempt to run in any idle time period large enough
+  // to fit `aMinimumUsefulBudget`. If no such window occurs within `aMaxDelay`
+  // ms, it will stop waiting for idle time and run from a TYPE_ONE_SHOT timer.
   static already_AddRefed<IdleTaskRunner> Create(
       const CallbackType& aCallback, const char* aRunnableName,
-      uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
+      uint32_t aMaxDelay, int64_t aMinimumUsefulBudget, bool aRepeating,
       const MayStopProcessingCallbackType& aMayStopProcessing);
 
   NS_IMETHOD Run() override;
@@ -46,9 +45,8 @@ class IdleTaskRunner final : public CancelableIdleRunnable {
 
   void SetTimer(uint32_t aDelay, nsIEventTarget* aTarget) override;
 
-  // Update the non-idle time budgeted for this callback. This really only
-  // makes sense for a repeating runner.
-  void SetBudget(int64_t aBudget);
+  // Update the minimum idle time that this callback would be invoked for.
+  void SetMinimumUsefulBudget(int64_t aMinimumUsefulBudget);
 
   nsresult Cancel() override;
   void Schedule(bool aAllowIdleDispatch);
@@ -56,7 +54,7 @@ class IdleTaskRunner final : public CancelableIdleRunnable {
  private:
   explicit IdleTaskRunner(
       const CallbackType& aCallback, const char* aRunnableName,
-      uint32_t aMaxDelay, int64_t aNonIdleBudget, bool aRepeating,
+      uint32_t aMaxDelay, int64_t aMinimumUsefulBudget, bool aRepeating,
       const MayStopProcessingCallbackType& aMayStopProcessing);
   ~IdleTaskRunner();
   void CancelTimer();
@@ -74,9 +72,8 @@ class IdleTaskRunner final : public CancelableIdleRunnable {
   // The null timestamp when the run is triggered by aMaxDelay instead of idle.
   TimeStamp mDeadline;
 
-  // The expected amount of time the callback will run for, when not running
-  // during idle time.
-  TimeDuration mBudget;
+  // The least duration worth calling the callback for during idle time.
+  TimeDuration mMinimumUsefulBudget;
 
   bool mRepeating;
   bool mTimerActive;