For a few weeks now, I've noticed that Firefox will not open properly and gets hung with a rotating circle. I have tried all of the conventional fixes including installing a new version but it doesn't seem to work. In the meantime, I will use Safari and occasionally, up to an hour later, it will open and operate normally...until I restart my Mac at which point the whole process starts all over again. But usually, I just get the finder message "Firefox not responding"

Please advise.