Painter 12 sluggish performance on Lion ?

I have OSX Lion Developer preview 4 installed on my machine.  This morning I installed Painter 12 on it, and found that the performance was pretty darn sluggish.  I wonder if it's the problem of the Lion beta or the Painter 12.

On the other hand SketchBook Pro 2011 works in silky smooth way, and so is Flash CS5.