Can you post what specefic games it lags in? could also be that you have vsync turned on. Try turning v sync off (if you have it on) in nvidia control panel and then let geforce experience optimize your games
v sync limits your fps so you might experience low fps but is your v-sync turned off in nvidia control panel (right click on start screen, click on nvidia control panel, click on manage 3d settings and turn it off)
but the gtx 760 isnt really the best gpu that is out on the market so i understand that you lag alot if you for an example put bf4 on full ultra and lagged