Computer Help and Support

~$ whatis top
top (1) - display Linux processes

Shift-p will show you the most cpu-intensive processes
Shift-m will show you the most memory hogging processes

You can kill offenders by the pid shown in top.
(killall kills processes by name, which you might not know when they start misbehaving).

Sometimes-useful header information shown by top:
top - 06:17:35 up 70 days, 7:38, 0 users, load average: 0.19, 0.52, 0.52
Tasks: 164 total, 5 running, 159 sleeping, 0 stopped, 0 zombie
%Cpu(s): 3.4 us, 1.7 sy, 0.0 ni, 94.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
MiB Mem : 3930.1 total, 1111.3 free, 1189.2 used, 1629.6 buff/cache
MiB Swap: 2947.5 total, 2863.0 free, 84.5 used. 2600.2 avail Mem

Ok, so I'm using an ancient, memory starved system. It's working for now.