I tend to record a lot of takes, which means I hit the Mute buttons quite often in the take lanes.  I had this problem with X2, and it's still there in X3:  When clicking several mute buttons in succession when play is stopped, after the first, the mute button image does not change for more than a second.  One time it took several seconds.  Anyone else have this problem?
I am still using a Win 7 system.  X1 never did this on my system.

I don't see that at all... have a current project with 20 takes on two tracks each.. mute/unmute occurs as fast as I can move the mouse.

yep X2/X3 not as light on the graphic engine as X1 , at least this is what i feel ..even switching screen sets ...

How much ram on your video card?