--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -1165,19 +1165,22 @@ toolbarpaletteitem[place="palette"] > #d
 }
 
 #BMB_bookmarksPopup[animate="cancel"] {
   -moz-window-transform: none;
 }
 
 %elifndef MOZ_WIDGET_GTK
 
+#BMB_bookmarksPopup {
+  will-change: transform, opacity; /* workaround for bug 1414033 */
+}
+
 #BMB_bookmarksPopup:not([animate="false"]) {
   opacity: 0;
-  will-change: transform; /* workaround for bug 1414033 */
   transform: translateY(-70px);
   transition-property: transform, opacity;
   transition-duration: 0.18s, 0.18s;
   transition-timing-function:
     var(--animation-easing-function), ease-out;
 }
 
 #BMB_bookmarksPopup[side="bottom"]:not([animate="false"]) {

--- a/toolkit/content/xul.css
+++ b/toolkit/content/xul.css
@@ -474,19 +474,22 @@ panel[type="arrow"][side][animate="open"
 }
 
 panel[type="arrow"][side][animate="cancel"] {
   -moz-window-transform: none;
 }
 
 %elifndef MOZ_WIDGET_GTK
 
+panel[type="arrow"][side] {
+  will-change: transform, opacity; /* workaround for bug 1414033 */
+}
+
 panel[type="arrow"][side]:not([animate="false"]) {
   opacity: 0;
-  will-change: transform; /* workaround for bug 1414033 */
   transform: translateY(-70px);
   transition-property: transform, opacity;
   transition-duration: 0.18s, 0.18s;
   transition-timing-function:
     var(--animation-easing-function), ease-out;
 }
 
 panel[type="arrow"][side="bottom"]:not([animate="false"]) {