Two processes doing extensive calculations – I want one to get ~100% of processor time – how?

I am running Ubuntu basic server with two processes: – process 1 – performing calculation 100% of uptime, and which I use to share computing power to community (it’s running @ prio 19) – process 2 – performing calculations for 5-10mins, from time to time, which I use to compute for me (it’s running @prio -19)

I want process 2 to be given with 100% of computing power (process 1 is at that moment should get close to 0% of CPU). But best what I get is 50% of CPU for process 1 and 50% of CPU for process 2 (checked with htop).

I don’t want to manually stop/start any process when I need computing power (both processes must be running all the time); 100% of CPU for process 2 must be given automatically.

What should I do to achieve my goal? Thanks.