On the same web, Edge is using 153.8 MB, Chrome 0255.8, Firefox 565.9. Why & is this going to be fixed?
These results are in Task Manager when all 3 browsers are on on the same page:
Those results definitely aren't typical, I'm seeing Firefox using around 220 MB when opening the same page in Windows 10. Can you try restarting Firefox in safe mode using these instructions: Troubleshoot Firefox issues using Safe Mode, and see what the memory usage is like? This will temporarily disable all of your addons, in case one of them is causing the issue.