Had all of these issues with Firestorm - freezing and random crashing. Had just upgraded Firestorm without doing a clean install. Finally carefully spent the time to delete all old settings for all viewers (had tried Alchemy and Kukua also - same issues). With the clean install has been trouble free in all viewers for two days now (knocking wood). Another advantage is the iMac fan doesn't spin up to full speed any more, even at higher resolution settings which would crash my viewers really quickly before.
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