If you find that display performance is not what you'd like it to be
using EXA, try adding this line:

Option      "MigrationHeuristic"     "smart"

to your xorg.conf.  I know that as of 1.3.0.0 (perhaps earlier), the X
server defaults to "always".
The problem here is that many drivers do not accelerate every EXA
operation, and so performance
can suffer.  If you run a compositor and it eats up CPU time even
though it's idle, you're almost certain to benefit from this.  Using
this option, I get far better performance using a compositor than I
get using either EXA or XAA with or without one.

There is another choice for "MigrationHeuristic" which is "greedy".
Try that if "smart" doesn't help.

In the coming weeks I'm going to be compiling all of the information I
have into a NetBSD "DRI How-To" guide.

Regards,

--Blair