On Mon, 2008-05-05 at 23:32 +0200, Jens M Andreasen wrote: > > clock: 4020 ms (_Complex) > > clock: 1550 ms (cvec_t) > > clock: 70000 ms (original float array[N][2]) Wait a second ... It's a trick! :-D The compiler splits the iterations up in smaller parts that fits in the cache and runs them in succesion.