GPU programs run fast exactly because programs are written with these limitations in mind. GPUs trade stuff like branch prediction for data parallelism. You can

GPU programs run fast exactly because programs are written with these limitations in mind. GPUs trade stuff like branch prediction for data parallelism. You can't just have both on the same die and achieve the same throughput. Using dynamic memory liberally, having lots of indirect branches and non-local memory access - that's pretty bad for performance on the CPU as well, even though it is optimized for that. It's just that people don't notice because they're used to programming that way.