When I have 15 tabs total (all windows) open, WHY do I have 38 Firefox processes running in my Task Manager???

[petpro]

When I have 15 tabs total (all windows) open, WHY do I have 38 Firefox processes running in my Task Manager???  And these processes are using resources (disk and memory) according to Windows Task Manager.  What am I missing and is there a way to correlate the processes running with the tabs in the the Firefox window.  Is Firefox misbehaving or are the websites the culprits?  Seems to me that Firefox should be shielding the user from nefarious (behind the scenes) resource robbing activity on my computer, unless of course, Mozilla is the culprit.

[siffemcon]

Totally normal; all browser use multi-process now. Go to about:processes via the address bar.

https://arstechnica.com/information-technology/2017/06/firefox-multiple-content-processes/

[dveditz]

As @siffemcon noted, the `about:processes` page will show you what is running where.

There are two reasons there are so many:

1. each "site" gets a separate process for security reasons ("Site Isolation"), but multiple tabs open to the same site might share a process
2. processes are kept running for recently visited sites for performance reasons, in case you go back to it (right-click on the back button to see each tab's Session History)

The processes for closed tabs should be using minimal amounts of memory and CPU (most of the memory is shared between processes), and they will be closed more aggressively if the machine is low on memory.

[Agentvirtuel]

Hello

Additional informations.

Firefox Profiler https://profiler.firefox.com (among other) https://profiler.firefox.com/docs/#/./guide-ui-tour-timeline?id=track-selection, you can click.