[The new Mac High Sierra TOS problem]

UPDATE: 

A friend suggested I should re-install Firestorm and after doing this I've experienced a significant improvement to my previous experience with High Sierra. Whether it's just a coincidence or not remains to be seen, but so far so good - fingers crossed

[The new Mac High Sierra TOS problem]

I am having the same trouble as you betsybb - I'm thinking the 'upgrade' to High Sierra was a big mistake - and all my problems began at that moment - a low frame rate, incredibly slow rezz times, crashing all the time, plus my avatar looks so much worse than it did before.