I too have given the new version a real hammering over the past few days,, working almost non stop for 18 hours a day,,,, I have only experienced 6 crashes in that time and all seem to be specific
1/ Crashes after doing some serious changes to SYMBOLS --- not ewverytime and not for small changes,, but almost always for large changes (EG: changing order of menu buttons) Deleting or adding buttons/dropdowns) changing menu type
2/ Seems to crash or get stuck in Typography,, especially changing Font Type, & Font Weight (can take a minute or so for the change to happen (usually if this happens, it will crash the nect time there is a change made
3/ This one is more random,, but it has crashed a couple of times,, when going to "Preview On" (I also noticed that it happens if I forget to save the changs before doing Preview On.
HOWEVER having said all that,, this version of FF is by far and away more stable with less crashes/hanging than all of the other,,, --- So yes thank you CC team,,, almost there
Love the new version and all it's bits--- by the way.