I did a clean install of 18.10 -- new LVM, partitions, etc. Now, it seems I type too fast for the system (I had to backspace painfully slow to erase the t in system so I could insert the s after y!). From the parenthetical you can see that the wait period before I can hit the same key is excessively long, and is not re-initiated by typing an intervening key. Indeed, I can sometimes type two different keys before hitting a given key a second time. The only thing System -> Universal is speed up how many copies of a given key are entered in a given time frame. I've gone so far as to turn repeat key off; meaning that I can hold down a given key forever and it won't repeat. Even so, typing see (or hitting backspace multiple times) takes nearly tow seconds because of waiting before I can hit the second e!
I also installed dconf, and set the defualt values to 30 for delay and 7 for repeat interval. I stil can't type repat at normal speed.