Opening a new empty tab is very slowly with the spinning wheel (about 10 to 20 seconds). With no other tab opened. Closing a tab also takes about more than 10 seconds (empy tab, no other tab). Can not open web sites : almost every times nothings happens. But sometimes it works. Firefox process has tenths of child processes which are <defunct> What I have tried : - Remove all configurations files (see list below) - Install a fresh Firefox - Restarts the computer (MacBook Pro Intel) - Launch Firefox That means that I have an empty profile, no external module, no account synchronisation, no history, no bookmarks, zilch, nada ... Repeated the previous procedures several times the last few months. With : - Mac OS X Ventura 13.5.1, Firefox 117.0 and Firefox 119.0 - Max OS X Sonoma 14.1, Firefox 119.0.1 - Mac OS X Sonoma 14.1.1, Firefox 120.0 - Mac OS X Sonoma 14.2.1, Firefox 122.0 Firefox has a normal behaviour for a few days after each system upgrade. Then the problems comes back. Other browsers (Chrome, Safari) works fine and smoothly. But ! TorBrowser, which is built on Firefox, encounter the same problems. Configurations files that I delete : - ~/Library/Preferences/org.mozilla.crashreporter.plist - ~/Library/Preferences/org.mozilla.firefox.plist - ~/Library/Caches/org.mozilla.firefox - ~/Library/Caches/org.mozilla.crashreporter - ~/Library/Caches/Firefox - ~/Library/Caches/Mozilla/updates/Applications/Firefox - ~/Library/Saved\ Application\ State/org.mozilla.firefox.savedState - ~/Library/Saved\ Application\ State/org.mozilla.updater.savedState - ~/Library/WebKit/org.mozilla.firefox - ~/Library/Application\ Support/Firefox - ~/Library/Application\ Support/Mozilla /Library/Application\ Support/Mozilla Can not find anything to try. Any idea ?