diff --git a/browser/components/customizableui/src/CustomizeMode.jsm b/browser/components/customizableui/src/CustomizeMode.jsm
index f3e822deca94..b9cb38c9baea 100644
--- a/browser/components/customizableui/src/CustomizeMode.jsm
+++ b/browser/components/customizableui/src/CustomizeMode.jsm
@@ -189,6 +189,11 @@ CustomizeMode.prototype = {
       // Hide the palette before starting the transition for increased perf.
       this.visiblePalette.hidden = true;
 
+      // Disable the button-text fade-out mask
+      // during the transition for increased perf.
+      let panelContents = window.PanelUI.contents;
+      panelContents.setAttribute("customize-transitioning", "true");
+
       // Move the mainView in the panel to the holder so that we can see it
       // while customizing.
       let mainView = window.PanelUI.mainView;
@@ -253,6 +258,8 @@ CustomizeMode.prototype = {
       this._updateEmptyPaletteNotice();
 
       this._handler.isEnteringCustomizeMode = false;
+      panelContents.removeAttribute("customize-transitioning");
+
       this.dispatchToolboxEvent("customizationready");
       if (!this._wantToBeInCustomizeMode) {
         this.exit();
@@ -300,6 +307,11 @@ CustomizeMode.prototype = {
     this.visiblePalette.hidden = true;
     this.paletteEmptyNotice.hidden = true;
 
+    // Disable the button-text fade-out mask
+    // during the transition for increased perf.
+    let panelContents = window.PanelUI.contents;
+    panelContents.setAttribute("customize-transitioning", "true");
+
     this._transitioning = true;
 
     Task.spawn(function() {
@@ -353,6 +365,8 @@ CustomizeMode.prototype = {
       document.getElementById("PanelUI-help").removeAttribute("disabled");
       document.getElementById("PanelUI-quit").removeAttribute("disabled");
 
+      panelContents.removeAttribute("customize-transitioning");
+
       // We need to set this._customizing to false before removing the tab
       // or the TabSelect event handler will think that we are exiting
       // customization mode for a second time.
diff --git a/browser/themes/shared/customizableui/panelUIOverlay.inc.css b/browser/themes/shared/customizableui/panelUIOverlay.inc.css
index 5152627671f5..45a48cd5e965 100644
--- a/browser/themes/shared/customizableui/panelUIOverlay.inc.css
+++ b/browser/themes/shared/customizableui/panelUIOverlay.inc.css
@@ -116,10 +116,14 @@
 .panelUI-grid .toolbarbutton-1 > .toolbarbutton-multiline-text {
   text-align: center;
   -moz-hyphens: auto;
-  mask: url(chrome://browser/content/browser.xul#menuPanelButtonTextFadeOutMask);
   min-height: 3.5em;
 }
 
+.panelUI-grid:not([customize-transitioning]) .toolbarbutton-menubutton-button > .toolbarbutton-multiline-text,
+.panelUI-grid:not([customize-transitioning]) .toolbarbutton-1 > .toolbarbutton-multiline-text {
+  mask: url(chrome://browser/content/browser.xul#menuPanelButtonTextFadeOutMask);
+}
+
 .panelUI-grid .toolbarbutton-1 > .toolbarbutton-multiline-text {
   margin: 2px 0 0;
 }