Problems that plague gaming laptops include overheating, programs running in the background, and the graphics card not running at the required speed (usually in MHz) for the game you are playing.
In order to avoid overheating problems, you may want to replace the fan(s) with better performing ones or give your laptop a rest and let it cool down.
In order to prevent programs from starting up while you are playing a game, manually go into the program (settings) and either turn off the program or schedule it to run while you aren't gaming.
In order to see if your graphics card is causing lag, look at the game requirements on the original packaging. Compare to the one running in your laptop. If the graphics card you have doesn't perform at the recommended capacity then you may need a better graphics card.