I just tested it on my machine, and I couldn't notice any difference in CPU.
As @alemabrahao says - I would try a different browser first.
There have been a lot of Chrome and Edge updates of late. Is your browser up to date?
Another test your could do is to open the case using incognito mode. This disables most extensions. If the problem goes away, you know it is related to one of the extensions in your browser.
Browsers often lean on the GPU quite a bit. If your machine has a dedicated GPU in it - you could try updating the GPU drivers.