Lag help pls

[kldnz]

hello i have a brand new laptopt. and i ran into a problem..... i was with windows 8... every game ran perfectly i played watch dogs on high graphics with no lag.... now i didnt like windows8... so i downgraded to windows 7... x64 and now when i play the same game "watch dogs" it even lags at low graphics what can be the problem?

 

[rgd1101]

reinstall drivers from the laptop manufacturer

 

[kldnz]

reinstall drivers from the laptop manufacturer

graphics card drivers?

 

[kldnz]

and if so where can i find a driver for AMD HD radeon 8750M please help i didnt find anything....