At the risk of sounding like a fanboy, it is noticeable only because Firefox patch management isn't all the good at the moment. It seems like the safest (and sometimes only) option is to download and reinstall the full app. At 5mb a download, that adds up; and then there is the underlying insecurity that an update is going to bork the profile.

Remove those problems and people won't notice as much or get quite so annoyed. 300k (or 1mb) is a lot easier to swallow.

So running bleeding edge, modded nightly builds has an advantage or two after all :) The fixes (and one other bugfix) are already in the nightlies, if you really can't live without your javascript.