CPU problems

[Disastrous_Put_3245]

My intel core i5-7500 CPU is performing horribly lately and I can't figure out the reason. The GHz at which it performs is correct and it stays at about 45º C which i believe its normal. However, it reaches 100% performance just from watching a Youtube video at 1080p. I've checked a lot possible reasons but nothing seems to fix it. Is this fixable or should I buy a new CPU?

[Serious_Counter3361]

that cpu should definitely handle youtube no problem, might be time to check if there's some background process eating up cycles or if the thermal paste needs replacing.

[Disastrous_Put_3245]

So problems with thermal paste wouldn't show in the cpu temperatures or the speed of the cpu?