Youtube 720 P 60 FPS suddenly lagging Helps pls ?

[Omar20019]

Hey guys , normally I watch all youtube videos on 720P 60 FPS with no problem smooth and fast and suddenly yesterday till now videos start to lag for no reason out of nowhere on same quality 720 P 60 FPS , and I checked my internet and restarted my router and nothing helped , even I've restarted my laptop and nothing also changed still same problem but some videos I can watch them with no problem on same quality and some of them lag that's weird because all videos were working just fine till yesterday that problem appeared , I even deleted my history , cookies etc... and nothing helped . Can u tell me solution pls ? should I format my laptop or is there anything app that can fix it ?

Thank You

 

[rgd1101]

laptop model? check driver?