Firefox not Responding (Mac & Windows 10) | Mozilla Firefox Won’t Open (2020- 2021)
Mozilla Firefox hangs and fails to respond at certain times. Here are some steps for how to fix Mozilla Firefox not responding. Press Ctrl + Shift +Esc keys together, which will open the Task Manager window. Now, under the Processes tab, find and select the Firefox browser. Click on the End Task button at the end of the window screen. Restart and launch the browser to check if the problem has solved or not.
For more details: https://contactforhelp.com/blog/mozilla-firefox-not-responding-on-windows-or-wont-open-on-mac/