Gustaf is right here. The AOLserver code does not take into account the size of the queue or the number of requests which could be served by a thread before allowing the thread to exit.
There is a basic logic problem in the code, but it really only shows up under test conditions. Two real world complicating factors are running very few threads (less than 10) and serving long running requests (slow client or huge data).
My experience is that external benchmark programs are less reliable than AOLserver, so it is very difficult to use their results. Most of the slowness in OpenACS will be in database queries, which will be impossible to detect using an external tool.
OTOH, if you expect hundreds of simultaneous visitors to a DB backed site, be happy with your success and look into distributing your site over a number of front end servers.
