OpenSolaris Or FreeBSD?
Norsefire writes "I am in quite a predicament. I decided a while back to branch out and use a new operating system (currently running Debian). After a bit of searching (trying Gentoo, Gobo and Arch along the way), I decided to use something that isn't Linux. Long story short: I narrowed the choices down to OpenSolaris and FreeBSD, but now I'm stuck. OpenSolaris is commercially backed by Sun, has nice enterprise-y tools in the default install, and best of all, a mature implementation of ZFS. FreeBSD is backed by a foundation, has a minimal default install and a rather new (but recently improved in the 8.0 release) implementation of ZFS, however it offers the Ports Collection (I quite like the performance boost due to compiling from source, no matter how small it might be) and a bigger community than OpenSolaris. That is just a minimal mention of the differences. I would be interested to see what the Slashdot community thinks of these two operating systems."
http://en.wikipedia.org/wiki/XOR_swap_algorithm
This maybe wasn't the best example since XOR swaps are rarely useful anyway. I suspect that other things like word (mis)alignment and varying cache miss costs may be a factor for different processors.
Gentoo claims that picking e.g. core2 over nocona can boost performance by 15% (which seems a bit much to me), so picking the right x86_64 variant is still something that is considered. Not something I worry about though, unless I am compiling from source anyway.