Wed Dec 07, 2011 12:11 am
Historically, the GPU was used for only a single task and there was no competition for that resource. So there was never any need to resolve any resource contention so the tools to deal with resource contention were never created. Only recently has general purpose GPU (GPGPU) usage started to become common.
When two activities are competing for the GPU resource, there will always be some form of performance issues till the graphics subsystem is totally revised. There is no priority or interrupt system or really anything that is built into the graphics subsystem to resolve resource conflicts. Currently, when you have two activities that compete to use the GPU something has to lose and often time it will be the thing that you don't want to lose i.e. the user experience because there is nothing there to decide which is important and which is not.
Folding on the GPU tries to use the GPU at 100%. Add something else like a game, playing a video, or even moving a window then it will have to wait for folding to give it a chance at the GPUand that is where the lag comes from. This problem is only going to get worse as GPGPU activities like using the GPU for browser rendering or video playing get more and more common.
At the moment, there are a very limited set of tools you can use to help solve your specific video-lag issues. The first, is choose your driver version carefully because that can matter a lot. Make sure you run Aero for that seems to help many at least for normal windows functioning like moving Windows around or mouse issues. Turn off using the GPU rendering in your browser, flash, or any other application that uses it. Do note that there may or may not be performance issues because many times there is an alternative pathway that allows the CPU to take over that function which may be sufficient or not depending upon your CPU's capabilities. Different video codec's will use more or less GPU and if you can't solve your lag problems you may be able to solve them by switching the Codec or configuring it differently. Try pausing GPU folding when starting an application that uses the GPU (like gaming or video playing) and restart it when you are done.
Someday, this issue will get solved, but not anytime quickly. It will require a combination of changes from HW, driver, OS, and applications.
P.S. I use 260.99 and for me, that driver version seems to work quite well in preventing lag.