PlanetLisp has this snippit regarding high-performance CL network servers:
Joel Reymont is having problems getting details on how best to do a high perfomance network server in lisp. The main problem seems to be that the various Common Lisp network servers are threaded and each thread takes up 2-4MB of heap. This limits the amount of threads that can be spawned.
With Erlang I can just launch a process to handle my incoming request, one process per request, without worries. I'm using Allegro CL, a top-notch Lisp implementation and I have to worry that each thread is gonna eat up 2-4Mb of memory. There seems to be no guidance or established pattern on how to write a high-performance network server in Lisp.