candle flame without particle emitter

Hi - I was working on a flame effect using a particle emitter which worked great until I tried to deploy it on an iphone, and it doesn’t perform well at all - despite doing as much as possible to optimize and reduce the emitter. So I’m looking to achieve a flame effect with something other than a particle emitter. The flame is a candle flame, so it doesn’t have to emit per-se. It could be a stationary, continuously burning flame, but I want it to be able to increase in volume or size, as well as sway from left to right based on user input. Anyone have any ideas?

Use an animated texture on a quad that always faces the camera. The quad can be scaled up as needed, and the top two vertices can be skewed to handle the “sway from left to right” part.