when the program is taking all CPU capacity at normal priority, then the various sytems responses are tuned down. So it might response quite slow on the mouse / keyboard, and then it may have to awake the video-part of the system. The solution is to lower the priority of the rendering process.

Note: even when rendering in low priority, I sometimes experience some slowdowns. Not on the mouse, but on the video-side of things.

Of course I cannot assure that this is the cause, but it might be worthwhile to look in this direction too.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though