I have this same issue on my Macbook. My setup is: GMA x3100 video card v10.5.7

Hardware Overview:

Model Name: MacBook
Model Identifier: MacBook4,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 4 GB
Bus Speed: 800 MHz
Boot ROM Version: MB41.00C1.B00
SMC Version (system): 1.31f0

I am working on a very basic sketchup model, I get a long lag time when I selected an area with the rectangle tool. I tried the Thawupinstallerbut it did not seem to help. Anyone know anything else that could be the root of this problem? Since I'm using SU7 will this not work for it? Thanks.