Browser window slowed down?

Moin, have a Firefox browser ask. For each window I have open, how much does this slow my laptop. I work with three screens and have around 20 windows open. Can you see that anywhere?

For each window I have open, how much does this slow my laptop.

This can't be answered in general, since it depends on the specific web applications / websites that are currently running in the individual browser windows. And on the performance of your computer (available RAM, CPU speed, hard disk speed etc.)

You can e.g. Load your computer (memory / CPU etc.) View in Windows in the Task Manager and in MAcOS in the activity display.

Thank you. I'm going to upload a picture.

Of course you can do it, but what's the use?

We also do not know by heart what power each window needs, which you have opened by chance, and how far it "brings your computer to its knees".

As I said: Nobody can answer that. You have to "measure" it yourself on your computer or simply try it out.