Hello guys. I need to ask a question on my laptop asus N45s with nvidia geforce 555m

The problem started when i cant play games duento the integrated graphic card in the global settings. This problem was settled by one of the threads in here. Later i fpund out that the games i was playong is still a bit laggy and is not fully satisfactory even with the 2g graphic card . Is this normal for latop or am i having problems with the settings of the graphic card. Im dissapointed in paying a lot of
Money not to get the best outcone somebody please help me . By the way the game i was playing is assasin creed 2 and the witcher 2 .. Thanks in advance