There isn't one answer for either desktop or server workloads, only trends. Some processor resources get cut in half between threads, some are duplicated and t

There isn't one answer for either desktop or server workloads, only trends. Some processor resources get cut in half between threads, some are duplicated and the threads compete for some others. If your favorite benchmark bottlenecks on a resource that's shared or divided between threads, it'll probably do worse with hyperthreading on; if that's not the case, and a lot of the instructions in the hot path can go to any decoder or ALU, it'll probably do better.