if the work can not be sent to another server, then starting a new
thread only makes it worse.

as long as you have more threads than cpus you will max the throughput.
 if you want the waits to be less queued (but longer for each request)
then bump up the number of asp.net threads. you overall thoughput will
be less (more context switches), but the request will be served fairly.

as you are compute bound there is no magic bullet. say you have a 4 proc
server, and 12 concurrent request. you have 24 secs of cpu, which can be
done in 6 secs if all 4 procs work at the same time. if you had 4
threads, then request would take 2 secs to process and be first come
first served. so some would be return in 2 secs, some in 4 secs, and
some after 6. if you had 12 threads, then all would return after 6 seconds.

your best bet is to lower the cost to < 1 sec by recoding the computation.

-- bruce (sqlwork.com)