Originally Posted by pzgren
No, a dream from you? RAM and CPU is always used, same goes for system processes. You can not freeze the whole other session or the other window manager and desktop applications like GNOME and nautilus, X,... running from using the CPU.
or maybe swap.
if the process has nothing to do - and waiting for input, without even being displayed is a very good definition for 'nothing to do' it needs no CPU. It is just waiting for the moment, it get back on display and has to react to some mouse/keyboard events.
You can freeze the other session, in fact, if the other session does nothing than waiting for input, so does not load websites, plays videos or music, it will have no impact.
By the way, you can freeze it in the real way: sigstop.
But that is not needed.