I had the same issue with browser tabs. It’s a “by design” feature of every browsers to minimize the processor activity when the tab is not visible, and they always try to improve this. I tried Edge, Firefox, Brave, Opera, Chrome and less known browsers but all had exactly the same behavior 🙁
There are tutos to change some advance configuration to disable this but I never found any that really works.
The only way (I’ve found) is to separate the tabs and keep them all visible.
Another way that I use now, is to create some virtual machines, and on each machine I run one browser, and I’m very happy with that system, because my settings stays the same on each machine when I restart the browser, as EA studio saves last configuration when the browser is closed.
And with all the tests that’s I’ve made, I got better results with chrome…