I'm on a system with 48 threads and the view for usage is taking up 4/5 of the vertical screen space. Is there a way to toggle the CPU usage window to just view the active PIDs?
You can’t toggle the top part of the screen in its entirety, but you can customize it. Press S to open the setup screen, then the right arrow to move to the column with the CPU entry, and Del to remove it. Esc will return to the main view.
Other variants are possible, for example the “CPU average” meter shows the average CPU use across all CPUs on a single line:
Whichever setup you end up with will be stored in
htop’s configuration file, so subsequent invocations will start as you left it.