Nglayout.debug.disable xul fastload
From MozillaZine Knowledge Base
The file to which the serialized data is saved differs by platform. On OS X it’s XUL FastLoad File; on Linux it’s xul.mfasl; and on Windows it’s XUL.mfl.
Possible values and their effects
Do not save serialized XUL/JS to disk.
Save serialized versions of parsed XUL/JS to disk for faster startup times. (Default)
First checked in
Has an effect in