nofam:K1000716: Overclocking mine to 1300mHz made the gallery much faster to load, also made hi-def videos load instantly when there had been a noticeable delay before. It made no appreciable difference to battery life.
What O/C app did you use?
The Cognition 1.06 kernel update has made a noticeable difference in speed, and I only losy 4% overnight with 3g sync going.? As someone here suggested a while back (or maybe it was XDA), the performance gains through tweaking ROM's will be limited with this device - the real gains will come through kernel dev. work.
I'm using Tegrak Ultimate, no good for users of the later cognition builds. Tegrak also lets you overclock gpu, possibly the only app to do that so far.