Power Management Driver 1.50 may cause bad 3D performance.

I used system update to update these drivers for my T500:
Sound drivers, Intel WIFI drivers, Intel internet adapter drivers. Then I manully install the newest ThinkPad Switchable Graphics Driver 8.52.4.4-080919a.

Ater these, I found 3Dmark06 score dropped to about 2400 from previous 4300 in High Performance mode of switchable graphix. When I changed to discrete graphix rather than switchable graphix in BIOS, the 3dmark06 score went back to normal 4300. However, when I changed back to switchable graphix in BIOS and selected High Performance mode, the 3Dmark06 score still cannot exceed 2500...
At first I thought the reason is the Graphics Driver, but the old version 8.52.4.3 gave the same results -- bad performance when switchable...

Now I restore my system, and update all above drivers except the new Power Management Driver 1.50. The 3D performance is normal with 3Dmark06 score of about 4300.

I donot want to install Power Management Driver 1.50 again to directly prove it's the reason. The above things are indirective proof that Power Management Driver 1.50 may have some problems. If you are interested, you can try Power Management Driver 1.50 to see wether it influeces 3D performance. For normal users, I want to remind you "Donot install Power Management Driver 1.50 ".