m16 R2, lag and more

hi, I just got a new alienware m16r2 and it sometime lags when Im playing games very bad were it freezes and the game Im playing is not using much ram. When I have a app called discord open to talk to friends and play game it will lag and either make my labtop super laggy and also make me not in discord were im not able to hear or talk to them. Also even if I am playing a game and just have a browser open it takes most of my memory and also lags pretty bad. I thought this would be better than my 300 labtop but the only thing that I feel thats better is my graphics as the alienware m16 r2 lags way more than my cheap labtop thats able to do multiple things at once while this one is not. If theres a way to fix this that would be great.