WIndows 8.1 low gaming performance

Good evening. I installed Windows 8.1 and after that I installed all drivers from this link http://www.dell.com/support/drivers/ua/ru/uabsdt1/ServiceTag/Everything is working good, I got a latest updates. But after that I started to play in League of Legends and found, that my fps is good but the performance so low than in windows 7. I tried to install the latest driver from official site Intel and AMD but it was useless. I guess that the same trouble in all games.

Kindly ask you to help me, please!

Best regards, Vlad.