Comment 59 for bug 278078

From Launchpad bugreport (https://bugs.launchpad.net/bugs/278078):
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Gah! I just upgraded to Intrepid and this happens to me too. Left and down aren't much slower at repeating than the other keys, but all the keys are quite slow. I can get at most about 6 keypresses per second.

By twiddling with the keyboard repeat controls, xset r rate, and (oddly enough) turning "slow keys" on and off in Accessibility, I can create all kinds of strange behaviors:
* xset r rate allows me to get very fast key repeats... but they happen in a spaced out rhythm. That is, I get 5 keypresses at once, then a 1/6 second or so pause, then 5 more keypresses, and so on.
* If I turn on "slow keys" in Accessibility (oddly enough), I get almost the behavior I want... except that left and down don't repeat _at all_, which is of course a dealbreaker.
* If I set the key repeat delay too low, I get the repeat rate I asked for... for about half a second. Then it slows down to 6 per second.
* If I use xset r rate and move the key repeat sliders anywhere in the Keyboard control panel, it goes back to the slow rate.

I assume from this behavior that there are two things competing for the keyboard repeat rate.

https://bugs.edge.launchpad.net/bugs/264196 seems to be describing the same issue, but over there they've found a few workarounds! Here's the one that worked for me with the least nasty side-effects:

Add this to the end of xorg.conf:

Section "ServerFlags"
Option "AutoAddDevices" "off"
EndSection

The downside is that any extra keys on your keyboard (such as "multimedia keys") won't work.