@zalex108
That problem stays here for more then 2 years now, over many generations and versions of Opera, regardless which Windows version is used.

I switched hardware in the last years (Intel to AMD CPU, older to newer AMD GPU), still the same. Windows 10 Pro all the time.

Firefox does use way less CPU in general for that task and also makes no difference between with sound and muted tab.

All that combined looks weird for Opera.