I've been working with GPUs for many years now and I still get surprised by their performance: some things turn out to be so bloody fast that I initially think

I've been working with GPUs for many years now and I still get surprised by their performance: some things turn out to be so bloody fast that I initially think that i must do something wrong. Other times, CPU implementations run circles around the GPU for no obvious reason. It's not intuitive and I still have a hard time wrapping my head around how fast these things are when they are at their best.