I would love to see what performance figures an asynchronous 6502 gets. It won't be anywhere near the performance of the Intellasys chips though (or, now-a-days, Green Arrays, as Chuck Moore has left Intellasys over various business-related issues).
http://forum.6502.org/viewtopic.php?t=1496&sid=52edaa9db48eea5c04888c59958f70bc