Hi folks, The similar question most probably has been discussed many times, but I really cannot find a clear answer. There are some obvious thinks like 64-bit addressing, but how about math calculations performance? I've set up two identical virtual machines in vbox - one with Arch x86_64 and another with Arch i686. I ran mencoder in both over the same video and got the following figures: x86_64: 43 sec i686: 34 sec which make x86_64 not so impressive ;) Some time ago I read an article at AMD web site, they suggested using their math libs for writing programs instead of standard ones. In such a case a program with complex math involved can performs much better (personally I haven't tried). I'm just curious about other people's opinions on this subject. Cheers, Sergey