Is using "other" Firefox 3 worth it?

[Fixman]

I once heared that the version of Firefox on the internet page crashed less than the synaptic one, and that it worked very much faster if compiled with -O3 (which I know how to do so please don't waste your time telling me how). Is one (or both) of these two really true?

[tel93]

Wll you're compiling specifically for your machine, so it should be faster.