I/O is still often the bottleneck. My laptop can handle 11 GB/s through RAM (and no NVME, so under 1 GB/s through the hard drive), less with unpredictable I/O p

I/O is still often the bottleneck. My laptop can handle 11 GB/s through RAM (and no NVME, so under 1 GB/s through the hard drive), less with unpredictable I/O patterns (like a hash-map) and 7600 GB/s through the CPU. Unless the thing you're doing is particularly expensive per byte of data, you're going to be limited at a minimum by RAM I/O, and maybe by DISK I/O. FWIW, all my recent performance wins have either been by reducing RAM I/O or restructuring work to reduce contention in the memory controller, even at the cost of adding significantly more work to the CPU.