Quick question.
Would I see any performance benefits from building my own custom kernel?
Probably not.
I build my own simply because I use some third party modules (ie tiser) and building a vanilla, with gcc 2.95.3, is generally going to be the least problematic in that scenario.
Now I do some customization beyond that - but it's mostly just removing modules I know I'll never need - that's mainly though to radically reduce the time it takes to build the modules when I do compile my own.