With AOLserver 3.3+ad13 I believe the defaults are minthreads 0,
maxthreads 20, threadtimeout 120. No, you probably wanted to
increase your values for all of those.
Good values are reportedly very hardware and operating system
specific, but since most of us are using Linux with a 2.4.x kernel, it
would be nice to see AOLserver tuning reports there. I haven't seen
any though.
Since you are sharing the server with other OpenACS instances, maybe
setting minthreads 5, maxthreads 30, threadtimeout 600 would be good
for you. If it was the only site on the box, perhaps minthreads 35,
maxthreads 35 would be more appropriate. But I don't really know for
sure, I just made up those numbers.