Any video i play freezes/glitches, and my comouter is just generally slow

I have a lenovo b50 touch laptop that I just got in September. Everything had been working great until about a week ago. My internet connection and ethernet connections are great(I had them checked by IT), but it takes forever to load a webpage and when i stream netflix, or any video, the picture freezes but the sound continues to play. I reload the page and then it will play almost normally for a little while but then both the picture and the sound start glitching and freezing. I have defragged and optimized my system multiple times, and my antivirus(webroot) says everything is fine. Any suggestions would be fantastic thanks!

The laptop itself may be broken. Where did you get it?
Try to reset it to factory settings and see if that works.