GPUs do have much better gate density, and better clock speeds, but the problem here is so specialized that the improved raw speeds of a GPU don't remotely make

GPUs do have much better gate density, and better clock speeds, but the problem here is so specialized that the improved raw speeds of a GPU don't remotely make up for its inflexibility. Additionally, GPUs are optimized for throughput. CPUs are optimized for latency, I haven't seen the benchmarks but I'd blindly bet that a modern CPU could get lower latency on this problem than a modern GPU. The blog post here solved the entire problem in just 3 clock cycles. I don't know how the numbers come back on a GPU or CPU, but the vast majority of the optimizations here are completely impossible on a standard instruction set, and would instead require doing dozens to hundreds of clock cycles. Going from 65 MHz to 5 GHz isn't going to make up for all the shortcuts you lose out on.