I use raw mplayer to play video, DeaDBeeF to play audio and Skype for VoIP. Heavy CPU-consuming processes (like rendering a website in Firefox, redrawing a Java IDE window or compilation) cause disturbances in multimedia playback processes. How to overcome this? I'd agree to those CPU-consuming processes to be a bit slower if it won't disturb multimedia playback.
to change a running process (as mentioned above :
or viva GUI
try playing with the "nice" command on a console (hint: man nice)
sudo nice foo –15 &
will start application foo at an "elevated" priority of -15 (less is more :D)
not exactly what you ask for, but try using the a realtime kernel, it's more responsive and the apps "seems to hang less".