Work though the Slow Laptop page on the Restart wiki (https://therestartproject.org/wiki/Slow_laptop), then, if you need to, come back with a more focussed question.
The first thing to establish: is the laptop slow generally (booting and launching programs) or is it only when you're browsing the Internet? If the activity light on your router is continually flashing while your laptop is connected, even when you're not loading pages, you could have something bad on your laptop or your router which is eating up your bandwidth. Easy thing to try: switch your router off and on again.