--- a/browser/themes/shared/tabs.inc.css
+++ b/browser/themes/shared/tabs.inc.css
@@ -196,16 +196,24 @@
      however, that currently forces main thread painting. When this is fixed
      (after WebRender lands), we can do something like
      `transition: fill 0.333s, opacity 0.333s;` */
 
   fill: currentColor;
   opacity: 0.7;
 }
 
+%ifdef NIGHTLY_BUILD
+@supports -moz-bool-pref("browser.tabs.30FpsThrobber") {
+  :root[sessionrestored] .tab-throbber[busy]::before {
+    animation: tab-throbber-animation 1.05s steps(30) infinite;
+  }
+}
+%endif
+
 :root[sessionrestored] .tab-throbber[busy]:-moz-locale-dir(rtl)::before {
   animation-name: tab-throbber-animation-rtl;
 }
 
 @keyframes tab-throbber-animation {
   0% { transform: translateX(0); }
   100% { transform: translateX(-100%); }
 }