rate change is easy
I had the exact opposite problem as you were having: I was having twice as many letters show up as I was intending to type. While I dont know why anyone would want this setting on high, you can adjust the rate (at least in Mandriva 2006).
Go to your applications, then System - Configuration - KDE - Peripherals - Keyboard. From there you can change the rate and the delay of the keys, fixes both of our problems and I can still do this ssssssssssssssssssss.