Feature Request: Add flag for how many CPU threads should be used

[JohnAlcatraz]

When running this on the CPU, it would be nice to have a flag for setting how many threads it should be allowed to use. Sometimes it might make sense to not use all available threads, and sometimes using more than the available threads might also make sense.

Currently, I see that if I run this on my CPU (Ryzen 3950X), I get a consistent 58% CPU usage, so it appears to use too few threads for me by default. It would be nice to be able to bring it up to 100%.