Hello, This issue started a month or two ago. Previously, Firefox takes about 1 second to start. The next day, starting my computer, Firefox consistently takes about 5-10 seconds to start. Not only this, but it also takes 5-10 seconds for an already running Firefox to respond to links from external programs (e.g. Adobe Acrobat, Word), as well as opening a second Firefox window by clicking on the Firefox shortcut. Interestingly, everything is fast and smooth with normal browsing and opening a new window via Firefox Ctrl+N is fine. Other browsers and software have no issues (e.g. Chrome). This has been really frustrating as I'm heavily reliant on Firefox and I have tried the following methods to no avail: • Disabling all add-ons / Start Firefox in Safe Mode • Reinstalling Firefox with fresh / no profiles. • Disabling anti-virus software (ESET Internet Security) • Uninstalling anti-virus software • Flushing DNS and resetting adapter • [WORKED] Starting Windows in Safe Mode • Disabling start-up services and processes systematically without Windows Safe Mode [Firefox slow again] • Disabling all services [still slow] • [WORKED for a few days...] Clean reinstalling WINDOWS • [WORKED for a few days...] System Restore (in between restore points I did almost nothing to PC, did not install any new programs, etc.) Sounds like a software issue, but if you want specs: Intel 7700K, 16GB 3000MHz RAM, Z270, Nvidia 980 Ti, Crucial M500 SSD. What are your thoughts? To me, it seems like something that run in normal Windows mode is slowing Firefox to start. Possibly conflicting apps? But I couldn't figure out which. Obviously, I can't run Windows in Safe mode all the time, so I was wondering if you have a solution? Many thanks Cam