I was having the same problem (CPU would spike up precisely when the screen saver logo would fade). I noticed the problem when running Zoom Player to play DVDs as an external task, picture would stutter every 10 sec). I have an Athlon X2 4200+ and a GeForce 7300, so I was surprised to see a simple fade put a drain on the system.
I switched to the screen saver plugin and the spikes have gone away.
I noticed 2 things about this problem:
1. It only happened when PVRX2 was not the foremost window (e.g., ZoomPlayer was running as an external task. If PVRX2 was the foremost window, the CPU wasn't spiking.
2. My computer is connected to a TV (S-video) and VGA monitor in clone mode. Not sure if that was impacting the problem.