Most distribution installs of apache2 have no apxs command for example :(
1. You are highly, highly unlikely to find anything compiled out by default that you need. Bear in mind that apache is very modular.
Compare the speed of SSL with and without SSE2.
Performance gains by compiling for SSE2 or whatever are negligible, and make even less difference to End User Experience
When I compile something I need thats not in the standard distro package archive I pack it into a deb. I then run my own package archive locally (really, it's not as scary as it sounds). That way I get the benifit of apt-get without sacrificing the ability to run my own versions of the software I need.
Managed packages are far easier to keep up to date
Obviously having compile tools on your server is a bad idea. Thats why you should have a Linux desktop box for doing all your 'development' work. :)
A compiler is a great thing to have on somebody else's server (that you're trying to root!) not your own