Related: when I worked on a server (on linux) that would spawn threads for new connections that were mostly short lived, I tried to use a thread pool instead. Hand crafted, with push and pop both O(1). It was still mostly slower than just spawning a new thread every time.
It's generally considered the right move to just spawn your own thread for things like connections instead of pooling threads - people tend to think they should throw everything into a threadpool but it's not actually encouraged to do that for stuff like web server connections, compiles, etc unless the task is short-lived. I wish more people knew that going in :) Some threadpool APIs actually ask you whether the job is going to take a while and if it is, they function more as a job limiter - not 500 active threads all competing for CPU - than a thread reuser.
