Look around in your browser for a setting about hardware acceleration.
Turn it on or off and test.
For about a year now i've been getting freezes while watching videos on youtube, while the freeze happens my audio cuts off, fans stop spinning and my screen freezes after that period of time the fans start spinning and everything is ok but it still occurs when i watch videos. While i play video games it's fine no stutter no lag very good fps on 1440p but it only happens when i watch youtube.
Graphic card: GTX 1080 MSI Gaming x
Ram: Corsair Vengance 2x4 8gb 3000mhz
Motherboard: ASUS ROG STRIX Z370-E GAMING
SSD: Samsung SSD 960 EVO Nvme M.2 250GB
HDD: Seagate BarraCuda 3.5'' 1TB SATA3 7200RPM 64MB
Psu: Corsair RM650x