Having multiple instances of Firefox running simultaneously can be caused by extensions, session restore settings, hardware acceleration, malware, or other factors. To address this issue, try disabling extensions, adjusting session restore settings, disabling hardware acceleration, running a malware scan, updating Firefox, and checking for interference from external applications. If the problem persists, consider creating a new Firefox profile or seeking assistance from the Firefox support community.
Multiple instances of Firefox running simultaneously might occur due to its multi-process architecture, designed for stability. Each process manages different tasks, contributing to memory efficiency and preventing a single crash from affecting the entire browser. While it may appear as high memory usage, this approach enhances performance and isolates issues.
Several processes, running, it's normal, it's Electrolysis, e10s
About Firefox multiprocess https://developer.mozilla.org/fr/docs/Mozilla/Firefox/Multiprocessus_Firefox
Sorry, the page /fr/docs/Mozilla/Firefox/Multiprocessus_Firefox could not be found
With the help of https://web.archive.org
Here's an archived page https://web.archive.org/web/20201020175640/https://developer.mozilla.org/fr/docs/Mozilla/Firefox/Mul...
Enter in Firefox address bar about:telemetry#search=e10s
e10sMultiProcesses, is, level about:config https://support.mozilla.org/en-US/kb/about-config-editor-firefox
dom.ipc.processCount (default) is 8
Previously, depending on Firefox version illustration Firefox's performance setting
Content process limit https://web.archive.org/web/20211228065714/https://support.mozilla.org/en-US/kb/performance-settings
Firefox's performance settings https://support.mozilla.org/en-US/kb/performance-settings
It is possible via a "manipulation" of e10sEnabled false, but it's useless
"C:\Program Files\Mozilla Firefox\firefox.exe"
Copy the above code (example) into Notepad
Type : All files
Then to start Firefox
Click on your illustration.bat file
For your information
If you try e10sEnabled false, then, see also the about:logins side effect
But this is nothing new
Other information about:memory https://firefox-source-docs.mozilla.org/performance/memory/about_colon_memory.html
Click on the "Measure..." button