Today, I discovered sth strange. OK here we go:

I installed bt4 beta on a macbook pro (not the latest unibody but the latest 17" before unibody version). I benchmarked a wpa attack with aircrack-ng
and got about 1000 Keys/s. I did the same with cowpatty and got about 100 Keys/s.

For THIS benchmark I didn´t used any FPGA.

But how can this huge difference between aircrack and cowpatty be explained?
Am I missing something?