Skype video makes my PC super slow

Question

I am a regular user of skype video calls. I have a very fast quad core PC with 4GB of ram. My machine has run perfectly well with skype till now. Now as soon as I start a video call, my PC becomes super slow - even moving my mouse results in the pointer moving in jerky steps across the screen. Looking at task manager I can see that skype is using 33% of the CPU time and system idle process takes 67%.

Confusingly quite a few things have changed on my system recently. My AVG virus scanner has just asked to do a major update and I have installed a new router- a netgear DG834. I am wondering if either of those may be causing trouble.

Any ideas?

UPDATE: If I iconise the skype video window then my PC speeds up again.. and slows down again the moment I expand it.

UPDATE II: I should have mentioned that I have four monitors connected to my PC, driven by two dual output graphics cards. I have just found that the slowdown is dependant on which monitor I put the video window in. Everything is fine when skype is in my main monitor, and slow in any of the other three.

Answer 1

In response to Update II - video acceleration is always slowed down on the non-primary monitors. It looks like either your graphics cards, or the video driver, or some combination of factors are making it slow enough to be unpleasant on other displays. This is not entirely unexpected...more details about the machine might reveal a workaround, though.