> and simultaneous-multithreading is letting another thread use the now-idle resources. This can actually be worse due to context switch overhead and caches yo

> and simultaneous-multithreading is letting another thread use the now-idle resources. This can actually be worse due to context switch overhead and caches you were using getting evicted by the now running thread hitting the same issue. If you want to do this right you should be organizing your data so that the prefetcher and take advantage of it. All of those speculative things still have a cost.