Comment 61 for bug 93847

I don't know if this is a clue but it looked very strange:

Some time ago I noticed that every time I checked processes with gnome system monitor ntop would use a lot of cpu (50-100%). When I killed ntop system monitor would be killed too! It happened consistently. Eventually I removed ntop in synaptics. After that system monitor would use 80-90% cpu and it took several seconds to resize its window. I then reinstalled ntop and now it runs normal 5-20% cpu, I can kill ntop without side effect.

Still ntop is apparently started automatically by system monitor (apparenatly also other *top utilities like atop)