(rip old incinerate, you're missed)
Seriously, I do not buy the "old incinerate had performance issues" when so many of the mobs still use it and I never once saw FPS issues with old incinerate. It was just a skill that got overnerfed and that powercreep made irrelevant.
Please bring the original skill back, I miss it. It practically still exists but only on holy flame totem.
(apologies for the slightly off topic)
Almost no monsters use old incinerate. Lots of monsters (including the ones being discussed in this comment thread) use the non-totemified version of the Flame skill from Flame Totem, which looks superficially similar but is much simpler mechanically.