--- a/dom/performance/Performance.cpp
+++ b/dom/performance/Performance.cpp
@@ -228,10 +228,10 @@ Performance::ClearResourceTimings()
 DOMHighResTimeStamp
 Performance::RoundTime(double aTime) const
 {
-  // Round down to the nearest 5us, because if the timer is too accurate people
+  // Round down to the nearest 20us, because if the timer is too accurate people
   // can do nasty timing attacks with it.  See similar code in the worker
   // Performance implementation.
-  const double maxResolutionMs = 0.005;
+  const double maxResolutionMs = 0.020;
   return floor(aTime / maxResolutionMs) * maxResolutionMs;
 }
 
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1284,12 +1284,7 @@ pref("javascript.options.mem.gc_max_empty_chunk_count", 30);
 
 pref("javascript.options.showInConsole", false);
 
-#ifdef RELEASE_OR_BETA
-// Disabled in Beta and Release for now, see bug 1225406
 pref("javascript.options.shared_memory", false);
-#else
-pref("javascript.options.shared_memory", true);
-#endif
 
 pref("javascript.options.throw_on_debuggee_would_run", false);
 pref("javascript.options.dump_stack_on_debuggee_would_run", false);