I just read about LinuxDNA project to compile kernel with Intel's ICC compiler. For a start it's 2.6.22. So forget about recent hardware. Oh, did I mentioned that binary drivers don't work?
But, it has 40% speed improvement. I have said once or twice that Itanium never really worked with Linux because of poor gcc complier. I really hope to see end of x86 architecture it Itanium history has anything to teach us. :-)
O.K, let me elaborate a bit: 40% speed increase available only with propriatory compiler is just enough for me not to buy another x86 processor if I had any realistic alternative.
With low power AMD solutions like SheevaPlug and AMD netbooks this might be possible in future, but not right now.
What is my problem with ICC? Did you know that you have to change binary of ICC to make it support AMD processors? I did, although this page vanished from Internet.
Do you really want to compile your kernel with compiler like that?
If you are still thinking something like: hell, yes! 40% faster! (imagine dark chorus going geeeentooooo in background while reading this) Please explain to me how do you intend to compile binary for any x86 processor, not just Intel, for example for LiveCD?