OK, I tested with -1, and that seemed to do very little. I could see in ksysguard that all 8 of my cores were nearly maxed out. I tested with -2 next and that seemed to look the same as -1, but I wasn’t sure if that was placebo, so I tested with -7. That then had all 8 of my threads around 10-20% usage. So, this is so weird. It’s not limiting to specific threads like it does with the -jX parameter in Windows. It seems to spread the remaining usage among all the threads anyway, so I can’t get max performance from 1 thread in particular this way.
It’s still way better that I can reduce the total CPU usage. I guess I shouldn’t use subtraction though, because if I’m running this in a VM which has only 4 threads available, for example, -7 would really bust things. I’ll stick with -j5 or something so I get at least some headroom for other software.
I really wish I could limit it to 7 particular threads and have those 7 used to the max while 1 thread is conspicuously free, like I saw in Windows, but I guess that’s just a difference in how these OSes operate.
I hope this thread helps someone else in the future! Thanks again, Strit, for your help. This had been bugging me for months and the solution was so simple!