Youtube Stuttering maybe because of CPU

Hello,

I‘m having problems watching youtube in 1080p60. After 1-2 minutes it starts to stutter. I can watch 4K just fine.

I‘m thinking my CPU is the Problem, because im getting clockspeeds as low as 0,9 Ghz

My Specs:

i7 7700 Gigabyte B250-HD3P 16 GB Ram AMD RADEON Sapphire RX 580 8GB

Does anyone have a solution?

Thanks in regards.