2.0.1.CR1 and above (we had to a put a fix into the Seam scanner to make it VFS/JBoss 5 aware). AS5 also required some fixes so make sure you use beta3 or above.
Ales has also done (not sure if its finished yet) to make Seam much faster in AS5 head (post beta3).
Do you mean much faster that previous versions of AS5 or much faster than 4.2.x?
Is performance better on AS5 in general?
Much faster than beta3 of AS5.
Currently performance is not better on AS5, but I hope it will be :) I think the plan was to get the functionality complete, then look at performance.