With nobody at Apple handling the engineering problem of implementing user requests, we're stuck with what we got. So I highly recommend App Tamer by St. Clair Software (no affiliation), which lets you set how much CPU percentage each process can use:

https://stclairsoft.com/AppTamer/index.html

It does cost $14.95 USD, but it's given me my computer back for years now. I have Spotlight Indexer set to 10%, although I'm using an old version of macOS and don't know if that's mdutil now or if Apple has outsmarted its throttling. I also set web browsers to 10% when they're in the background. And you can always message the developer with feature requests.

A bit of a rant: I honestly feel that we've done process scheduling wrong in most OSs and apps. It should have always been up to the user, along with granting permissions as needed. And I can't believe that no web browser has implemented turning JavaScript off after perhaps 10 seconds for example, so that we can have as many tabs open as we want. Instead we've let the technology order us what to do. It's all just so wrong. But the barriers to entry for writing a new browser are so high that only large organizations can do it, and they choose not to, so help isn't coming. Although I think with the arrival of AI, we're going to start seeing real software again that makes a mockery of the status quo and hopefully eats its lunch.