Well the last time the thread thing bit me was actually a case where it wasn't premature optimization; I had written the code in such a way that I thought was pretty enough, and we were hitting bottlenecks, so my genius brain thought "ok I'll make this use 20 threads and it'll go faster". It did not.
Pretty sure I’ve made exactly the same mistake. I feel like everyone who ever writes concurrent code learns that lesson at some point. It’s absolutely astonishing how much mileage one can get out of thread-per-core-fed-by-work-queues architectures.
