Hi,
This is an idea that cPanel has implemented, when someone in the file manager zips something, the process automatically starts with renice set to 19, so the process consumes less server resources.
One of my friends was zipping a file and the load averages went to 11.00 11.34 10.45, I manually set the process with “renice 19 [pid]” and it went to 3.94 4.5 5.5 in no time.
Regards