FPS issues with laptop gaming when charger connected

I have a lenovo g505s laptop which has an AMD A10 processor, it has good components that allow me to play the desired games i have, i have an issue with the framerate though, i get good smooth FPS when the laptop is running from battery but when i insert the charger to the laptop my framerate drops significantly in some games even to the point where i'm unable to play the game, please help.