--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -506,16 +506,18 @@ pref("browser.bookmarks.openInTabClosesM
 
 // Scripts & Windows prefs
 pref("dom.disable_open_during_load",              true);
 pref("javascript.options.showInConsole",          true);
 #ifdef DEBUG
 pref("general.warnOnAboutConfig",                 false);
 #endif
 
+pref("jsloader.shareGlobal", true);
+
 // This is the pref to control the location bar, change this to true to
 // force this - this makes the origin of popup windows more obvious to avoid
 // spoofing. We would rather not do it by default because it affects UE for web
 // applications, but without it there isn't a really good way to prevent chrome
 // spoofing, see bug 337344
 pref("dom.disable_window_open_feature.location",  true);
 // prevent JS from setting status messages
 pref("dom.disable_window_status_change",          true);

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -5245,17 +5245,17 @@ pref("dom.idle-observers-api.fuzz_time.d
 // they are handled separately. This pref is only read once at startup:
 // a restart is required to enable a new value.
 pref("network.activity.blipIntervalMilliseconds", 0);
 
 // If true, reuse the same global for (almost) everything loaded by the component
 // loader (JS components, JSMs, etc). This saves memory, but makes it possible
 // for the scripts to interfere with each other.  A restart is required for this
 // to take effect.
-pref("jsloader.shareGlobal", true);
+pref("jsloader.shareGlobal", false);
 
 // When we're asked to take a screenshot, don't wait more than 2000ms for the
 // event loop to become idle before actually taking the screenshot.
 pref("dom.browserElement.maxScreenshotDelayMS", 2000);
 
 // Whether we should show the placeholder when the element is focused but empty.
 pref("dom.placeholder.show_on_focus", true);