--- a/js/xpconnect/src/xpcpublic.h
+++ b/js/xpconnect/src/xpcpublic.h
@@ -672,20 +672,26 @@ AreNonLocalConnectionsDisabled()
         }
     }
     return disabledForTest;
 }
 
 inline bool
 IsInAutomation()
 {
-    const char* prefName =
-      "security.turn_off_all_security_so_that_viruses_can_take_over_this_computer";
-    return mozilla::Preferences::GetBool(prefName) &&
-        AreNonLocalConnectionsDisabled();
+    static bool sAutomationPrefIsSet;
+    static bool sPrefCacheAdded = false;
+    if (!sPrefCacheAdded) {
+        mozilla::Preferences::AddBoolVarCache(
+          &sAutomationPrefIsSet,
+          "security.turn_off_all_security_so_that_viruses_can_take_over_this_computer",
+          false);
+        sPrefCacheAdded = true;
+    }
+    return sAutomationPrefIsSet && AreNonLocalConnectionsDisabled();
 }
 
 void
 CreateCooperativeContext();
 
 void
 DestroyCooperativeContext();