Hard to say, and I haven't looked at how much memory each AOLserver
thread takes up with the latest OpenACS. My fairly un-informed guess
is that 5 is probably fine for a Dev server but might be a bit low for
any public Production server. Maybe 10 would be a better default
value.
The important thing is probably to set the threadtimeout to something
reasonable, the default of 120 s is just horrible for most people
using OpenACS.
Threads are pretty fat -- It looked like roughly 12-20MB per thread if you install all the packages (it's less for just the core). I think leaving it at
5 with a BOLD comment that it should be increased for production sites
on dedicated boxes is probably the right answer.
Actually the right answer is to get ttrace working which would decrease that
footprint and thread create times immensely, but I tried and did not manage
it. I am sure Zoran would help though.