The other day I was scared; Firestorm suddenly had around 2.1 GB of RAM and climbing. I relogged, and things were back to normal, and they have been that way since. So, Firestorm isn't immune to the problem, it just doesn't seem to happen as often. What was different about that run? It is still a puzzlement.
UPDATE: It's happened a time or two, but last night all was well. Not sure what I can do other than keep my fingers crossed, but that makes it awfully hard to type.