GPU under load affect CPU decoding performance?

[Chengbin]

When I watch a 1080p video, using MPC-HC, ffmpeg-mt as decoder, Windows 7 (with the built in decoder turned off), and running Folding@Home GPU, my video stutters. It is clearly using the CPU to decode, as it is taking up a 20% of my quad core's CPU. As soon as I pause Folding@home, the playback becomes smooth.

How in the world does my GPU usage affect CPU decoding performance?

[Dark Shikari]

It's likely that what's being slowed down is the renderer in MPC-HC, not the decoder.

[Chengbin]

Ahh, thanks for the explanation.