I read the https://fedoraproject.org/wiki/Features/F12X86Support. IMHO optimizing for some ATOM specific CPU get 1% improvement, IMHO those are peanuts and not worthwhile to change anything at cost of loosing compatibility. ATOM and distro and applications running on ATOMs needs much much more boosts (BTW, I've ATOM 450 and I run directly the 64bit 2010.1 distro on it, so should be SSE2 optimzed at source, and IMHO it is still underpowered for plain tasks).

G.