there is not alot to that and it changes from version to version
you could possibly check out the new alternative kernel branches or investigate nitro patches mm patches preemtible patches and the like
there is a sourceforge project
can't look it up cause sourceforge seems to be down right now i think it's
http://fork.sourceforge.net
for the vanilla kernel
basically you build the kernel to only support exactly the hardware you have and absolutely nothing more
make everything accept sound built in and not modules cause modules require overhead,
sound doesn't seem to work correctly builtin.
hack the Makefile to add gcc optimization for your machine and be aggressive
make the build verbose so you can see what's going on to make sure your gcc optimizations are being applied.
after you get it running apply tweeks using /etc/sysctl.conf to open the network pipes with
net.core.rmem_max = 524288
net.core.wmem_max = 524288
and investigate i guess if more tweeks are needed or usefull
most specialty kernels also have specialty tweeks
wish i could give you a tweek site but like i said this stuff changes so much most sites are obsolete