Discrete graphics AMD is sluggish

hello people with mbp 2011 15" early 2.2Ghz

does anyone got this problem?
when my AMD 6750m 1GB is turned on, exposé and switching between windows is sluggish kind of lags and is not smooth at all! but when I turn Intel graphics it becomes a lot smoother

and I get 38fps on cinebench on the mac version and on windows I get 41-42 not overclocked
so is there something wrong with my GPU or is it simply bad a bad Driver?

the AMD is fine on bootcamp, it is actually more than fine