

this may very well be the case. I can not say for sure, my guess is that most cpus should be able to do something like 200mb/s zstd(3) uncompress, but you can try to benchmark uncompress speeds (there is also a zstd benchmark command), and if it is statistically significantly lower than your storage (use hdparam/dd to benchmark them), then it is indeed your cpu.
this but characters for me.