Hi st857, the Windows 10 Task Manager's "Processes" tab "Apps" section shows the number of separate processes used by an application. In Firefox there are a few processes shared across the browser and a number of processes shared by tab content. There is not a one-to-one correspondence with windows like the Windows 7 Task Manager's "Applications" or "Tasks" tab. If you want to exercise more control over the number of processes used for tab content, there is a setting for that: [[Firefox's performance settings]].