I have noticed a major decrease in hashing speed when I close my laptop lid, it goes down from 48M (Yes, I know it's low) to about 20M.
My power plan is always on high performance: hdd always on, no sleep/hibernate/anything else. Actually I always remove my battery when my laptop is on full throttle.
This only happens when my screen goes black, even when I close it for 3 seconds, I don't want to let it on for hours.
I use CGminer and GUIminer, same results.
AMD A8-4500M with Radeon HD 7640G, Win7/64, last drivers, everything is in order.
Any help is appretiated, thanks.

http://gpuz.techpowerup.com/13/04/22/4gp.png