With your laptop's configuration, internet should not lag.
Please check following things.
1. First make sure that your internet connection is good. Please try same internet connection in other devices or laptops.
2. Even if your internet connection is good, your modem/router may have some problem. Please reset your modem or router. Please go through your modem's manual for steps for resetting.
3. If you are done with above steps, then you should check your internet browsers. Try Chrome, Opera, Firefox and Internet explorer/Edge.
4. Then clear cookies, cache and internet history from your browser and they try surfing.
Hope it helps