Hi folks!

I have a WinForms application that uses XNA to animate 3D models in a control. The app have been doing just fine for months but recently I've started to experience periodic pauses in the animation. Setting out to investigate what is going on I have established these facts:

1. It (currently) happens on my machine only
2. Removing everything from my render loop does not improve the problem

In 2. I didn't actually remove everything, I limited my loop to set the viewport on my GraphicsDevice and then do a GraphicsDevice.Present.

Trying to dig further I fired up PIX to capture some statistics. Screenshots of two PIX runs can be viewed here (Run6) and here (Run14). Run6 is using my original render loop and Run14 is using the bare-bones Present loop.

PIX tells me that the GPU is periodically doing something, and I assume this is causing the pauses. What could be the cause of this? Or how do I go about finding out what the GPU is actually doing?

Note: I'm using XNA 3.1 on a Windows 7 x64 dual-core machine with 8GB RAM.

Note2: also posted this question on the XNA Creators forums here.