--- a/widget/windows/nsLookAndFeel.cpp
+++ b/widget/windows/nsLookAndFeel.cpp
@@ -60,16 +60,17 @@ static int32_t GetSystemParam(long flag,
     return ::SystemParametersInfo(flag, 0, &value, 0) ? value : def;
 }
 
 nsLookAndFeel::nsLookAndFeel()
   : nsXPLookAndFeel()
   , mUseAccessibilityTheme(0)
   , mUseDefaultTheme(0)
   , mNativeThemeId(eWindowsTheme_Generic)
+  , mCaretBlinkTime(-1)
 {
   mozilla::Telemetry::Accumulate(mozilla::Telemetry::TOUCH_ENABLED_DEVICE,
                                  WinUtils::IsTouchDeviceSupportPresent());
 }
 
 nsLookAndFeel::~nsLookAndFeel()
 {
 }
@@ -328,17 +329,22 @@ nsLookAndFeel::GetIntImpl(IntID aID, int
 {
   nsresult res = nsXPLookAndFeel::GetIntImpl(aID, aResult);
   if (NS_SUCCEEDED(res))
     return res;
   res = NS_OK;
 
   switch (aID) {
     case eIntID_CaretBlinkTime:
-        aResult = (int32_t)::GetCaretBlinkTime();
+        // eIntID_CaretBlinkTime is often called by updating editable text 
+        // that has focus. So it should be cached to improve performance.
+        if (mCaretBlinkTime < 0) {
+            mCaretBlinkTime = static_cast<int32_t>(::GetCaretBlinkTime());
+        }
+        aResult = mCaretBlinkTime;
         break;
     case eIntID_CaretWidth:
         aResult = 1;
         break;
     case eIntID_ShowCaretDuringSelection:
         aResult = 0;
         break;
     case eIntID_SelectTextfieldsOnKeyFocus:
@@ -734,16 +740,17 @@ nsLookAndFeel::GetFontImpl(FontID anID, 
 nsLookAndFeel::RefreshImpl()
 {
   nsXPLookAndFeel::RefreshImpl();
 
   for (auto e = mSystemFontCache.begin(), end = mSystemFontCache.end();
        e != end; ++e) {
     e->mCacheValid = false;
   }
+  mCaretBlinkTime = -1;
 }
 
 /* virtual */
 char16_t
 nsLookAndFeel::GetPasswordCharacterImpl()
 {
 #define UNICODE_BLACK_CIRCLE_CHAR 0x25cf
   return UNICODE_BLACK_CIRCLE_CHAR;

--- a/widget/windows/nsLookAndFeel.h
+++ b/widget/windows/nsLookAndFeel.h
@@ -71,16 +71,17 @@ private:
    */
   nsresult GetAccentColorText(nscolor& aColor);
 
   // Content process cached values that get shipped over from the browser
   // process.
   int32_t mUseAccessibilityTheme;
   int32_t mUseDefaultTheme; // is the current theme a known default?
   int32_t mNativeThemeId; // see LookAndFeel enum 'WindowsTheme'
+  int32_t mCaretBlinkTime;
 
   struct CachedSystemFont {
     CachedSystemFont()
       : mCacheValid(false)
     {}
 
     bool mCacheValid;
     bool mHaveFont;

--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -5205,16 +5205,21 @@ nsWindow::ProcessMessage(UINT msg, WPARA
         fontEnum->UpdateFontList(&didChange);
         ForceFontUpdate();
       } //if (NS_SUCCEEDED(rv))
     }
     break;
 
     case WM_SETTINGCHANGE:
     {
+      if (wParam == SPI_SETKEYBOARDDELAY) {
+        // CaretBlinkTime is cached in nsLookAndFeel
+        NotifyThemeChanged();
+        break;
+      }
       if (lParam) {
         auto lParamString = reinterpret_cast<const wchar_t*>(lParam);
         if (!wcscmp(lParamString, L"ImmersiveColorSet")) {
           // WM_SYSCOLORCHANGE is not dispatched for accent color changes
           OnSysColorChanged();
           break;
         }
         if (IsWin10OrLater() && mWindowType == eWindowType_invisible) {