This box has 4 cores so looks like it is affected. I was just saying that I also had this issue when we used to use Logmein on machines with the Matrox driver. Since most of the machines were headless we removed the matrox driver and installed the standard VGA driver and it worked fine so I'm guessing the Matrox driver just doesn't want to play ball.
I'll let you know if the problem goes away with the 6.3 release.
I'm also experiencing this issue. If you turn off hardware acceleration in the display settings there is an improvement in performance but not a drop in CPU usage. Also, make sure the colour depth is not set at 32 bit.
I also experienced speed issues using LogMeIn on this type of display adapter.
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