Here's a good easy fix for this problem from https://bugs.launchpad.net/ubuntu/+sour ... bug/264196
"wolfwitch wrote 12 hours ago: (permalink)
The workaround posted near the top of this bug, submitted by Jorge Peixoto de Morais Neto, seems to be the best fix for this for now. It works on my laptops and home desktop when using any keyboard...
kbdrate -r 25 -d 500
I just put it right above "exit 0" at the bottom of the file.
Frankly, I can't believe this hasn't been fixed yet."
I changed those figures a bit to repeat rate 15 and delay 750, which works for me.
Remember to restart after editing rc.local. This will make the fix work for all keyboards, including USB.