I don't think this is a USB driver problem, maybe more
along the lines of DMA turned off, or maybe the apm
daemon not playing nicely with your MoBo ...
Have a look at top's output, do you get CPU spikes
in during the periods of slow keyboard? Try killing
apmd if it's running ...
That said: RH is notorious for the fact that it fires
up a gazillion of little helpers you probably don't
need at all ... ;)