--- a/widget/windows/TSFTextStore.cpp
+++ b/widget/windows/TSFTextStore.cpp
@@ -1671,18 +1671,20 @@ TSFTextStore::FlushPendingActions()
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
                 "dispatching compositionstart event...", this));
         WidgetEventTime eventTime = mWidget->CurrentMessageWidgetEventTime();
         nsEventStatus status;
         rv = mDispatcher->StartComposition(status, &eventTime);
         if (NS_WARN_IF(NS_FAILED(rv))) {
           MOZ_LOG(sTextStoreLog, LogLevel::Error,
             ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
-             "FAILED to dispatch compositionstart event.", this));
-          mDeferClearingContentForTSF = false;
+             "FAILED to dispatch compositionstart event, "
+             "IsComposingInContent()=%s",
+             this, GetBoolName(!IsComposingInContent())));
+          mDeferClearingContentForTSF = !IsComposingInContent();
         }
         if (!mWidget || mWidget->Destroyed()) {
           break;
         }
         break;
       }
       case PendingAction::COMPOSITION_UPDATE: {
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
@@ -1698,30 +1700,34 @@ TSFTextStore::FlushPendingActions()
         // composition update.
         mDeferClearingContentForTSF = true;
 
         rv = mDispatcher->SetPendingComposition(action.mData,
                                                 action.mRanges);
         if (NS_WARN_IF(NS_FAILED(rv))) {
           MOZ_LOG(sTextStoreLog, LogLevel::Error,
             ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
-             "FAILED to setting pending composition...", this));
-          mDeferClearingContentForTSF = false;
+             "FAILED to setting pending composition... "
+             "IsComposingInContent()=%s",
+             this, GetBoolName(IsComposingInContent())));
+          mDeferClearingContentForTSF = !IsComposingInContent();
         } else {
           MOZ_LOG(sTextStoreLog, LogLevel::Debug,
             ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
              "dispatching compositionchange event...", this));
           WidgetEventTime eventTime = mWidget->CurrentMessageWidgetEventTime();
           nsEventStatus status;
           rv = mDispatcher->FlushPendingComposition(status, &eventTime);
           if (NS_WARN_IF(NS_FAILED(rv))) {
             MOZ_LOG(sTextStoreLog, LogLevel::Error,
               ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
-               "FAILED to dispatch compositionchange event.", this));
-            mDeferClearingContentForTSF = false;
+               "FAILED to dispatch compositionchange event, "
+               "IsComposingInContent()=%s",
+               this, GetBoolName(IsComposingInContent())));
+            mDeferClearingContentForTSF = !IsComposingInContent();
           }
           // Be aware, the mWidget might already have been destroyed.
         }
         break;
       }
       case PendingAction::COMPOSITION_END: {
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
@@ -1738,18 +1744,20 @@ TSFTextStore::FlushPendingActions()
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions(), "
                 "dispatching compositioncommit event...", this));
         WidgetEventTime eventTime = mWidget->CurrentMessageWidgetEventTime();
         nsEventStatus status;
         rv = mDispatcher->CommitComposition(status, &action.mData, &eventTime);
         if (NS_WARN_IF(NS_FAILED(rv))) {
           MOZ_LOG(sTextStoreLog, LogLevel::Error,
             ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
-             "FAILED to dispatch compositioncommit event.", this));
-          mDeferClearingContentForTSF = false;
+             "FAILED to dispatch compositioncommit event, "
+             "IsComposingInContent()=%s",
+             this, GetBoolName(IsComposingInContent())));
+          mDeferClearingContentForTSF = !IsComposingInContent();
         }
         break;
       }
       case PendingAction::SET_SELECTION: {
         MOZ_LOG(sTextStoreLog, LogLevel::Debug,
                ("TSF: 0x%p   TSFTextStore::FlushPendingActions() "
                 "flushing SET_SELECTION={ mSelectionStart=%d, "
                 "mSelectionLength=%d, mSelectionReversed=%s }, "
@@ -2020,20 +2028,21 @@ TSFTextStore::ContentForTSFRef()
       MOZ_LOG(sTextStoreLog, LogLevel::Error,
              ("TSF: 0x%p   TSFTextStore::ContentForTSFRef(), FAILED, due to "
               "GetCurrentText() failure", this));
       mContentForTSF.Clear();
       return mContentForTSF;
     }
 
     mContentForTSF.Init(text);
-    // Basically, the locked content should be cleared after the document is
+    // Basically, the cached content which is expected by TSF/TIP should be
+    // cleared after active composition is committed or the document lock is
     // unlocked.  However, in e10s mode, content will be modified
     // asynchronously.  In such case, mDeferClearingContentForTSF may be
-    // true even after the document is unlocked.
+    // true until whole dispatched events are handled by the focused editor.
     mDeferClearingContentForTSF = false;
   }
 
   MOZ_LOG(sTextStoreLog, LogLevel::Debug,
          ("TSF: 0x%p   TSFTextStore::ContentForTSFRef(): "
           "mContentForTSF={ mText=\"%s\" (Length()=%u), "
           "mLastCompositionString=\"%s\" (Length()=%u), "
           "mMinTextModifiedOffset=%u }",
@@ -4995,19 +5004,22 @@ TSFTextStore::OnUpdateCompositionInterna
      "mDestroyed=%s, mDeferNotifyingTSF=%s",
      this, GetBoolName(mDestroyed), GetBoolName(mDeferNotifyingTSF)));
 
   // There are nothing to do after destroyed.
   if (mDestroyed) {
     return NS_OK;
   }
 
-  // Now, all sent composition events are handled by the content even in
-  // e10s mode.
-  mDeferClearingContentForTSF = false;
+  // If composition is completely finished both in TSF/TIP and the focused
+  // editor which may be in a remote process, we can clear the cache until
+  // starting next composition.
+  if (!mComposition.IsComposing() && !IsComposingInContent()) {
+    mDeferClearingContentForTSF = false;
+  }
   mDeferNotifyingTSF = false;
   MaybeFlushPendingNotifications();
   return NS_OK;
 }
 
 nsresult
 TSFTextStore::OnMouseButtonEventInternal(
                 const IMENotification& aIMENotification)

--- a/widget/windows/TSFTextStore.h
+++ b/widget/windows/TSFTextStore.h
@@ -788,29 +788,34 @@ protected:
     enum : uint32_t
     {
       NOT_MODIFIED = UINT32_MAX
     };
     uint32_t mMinTextModifiedOffset;
 
     bool mInitialized;
   };
-  // mContentForTSF starts to cache content of the document at first query of
-  // the content during a document lock.  The information is expected by TSF
+  // mContentForTSF is cache of content.  The information is expected by TSF
   // and TIP.  Therefore, this is useful for answering the query from TSF or
-  // TIP.  This is abandoned after document is unlocked and dispatched events
-  // are handled.  This is initialized by ContentForTSFRef() automatically.
-  // So, don't access this member directly except at calling Clear(),
-  // IsInitialized(), IsLayoutChangedAfter() or IsLayoutChanged().
+  // TIP.
+  // This is initialized by ContentForTSFRef() automatically (therefore, don't
+  // access this member directly except at calling Clear(), IsInitialized(),
+  // IsLayoutChangeAfter() or IsLayoutChanged()).
+  // This is cleared when:
+  //  - When there is no composition, the document is unlocked.
+  //  - When there is a composition, all dispatched events are handled by
+  //    the focused editor which may be in a remote process.
+  // So, if two compositions are created very quickly, this cache may not be
+  // cleared between eCompositionCommit(AsIs) and eCompositionStart.
   Content mContentForTSF;
 
   Content& ContentForTSFRef();
 
-  // While the documet is locked, this returns the text stored by
-  // mContentForTSF.  Otherwise, return the current text content.
+  // While mContentForTSF is valid, this returns the text stored by it.
+  // Otherwise, return the current text content retrieved by eQueryTextContent.
   bool GetCurrentText(nsAString& aTextContent);
 
   class MouseTracker final
   {
   public:
     static const DWORD kInvalidCookie = static_cast<DWORD>(-1);
 
     MouseTracker();