Why is each open Firefox tab showing up in the Windows volume mixer?
If your Windows volume mixer has a slider for each open Firefox tab, this is a known issue related to multiprocess (E10s) and we are working on fixing it in the near future. In the meantime, setting the number of Firefox processes to "1" should fix the issue:
- Click on the menu button to open the menu panel.
- Click the menu button and choose . .
- In the General panel, scroll down to Performance.
- Remove the check mark next to Use recommended performance settings.
- Choose 1 in the drop-down menu for Content process limit.