Content Aware Fill Uses 97% of RAM then crashes

Content Aware fill really doesn't like long sequences. I've been trying to use it to remove some burned in camera HUD stuff from a misrecorded take on a show, and it can't process more than a minute or two's worth of footage (in 1080i) without sucking up all system application memory and then crashing. Hopefully future versions are a bit more robust.
This is a really interesting area of technology though, so I hope Adobe keep at it with their ML based development (and make better use of GPUs -  as far as I can tell, CA fill in After Effects barely touches the GPU)

Could be footage format, frame size, other effects in the comp, frame rate... a bunch of things.

The best way to use CAF is to trim the shot you want to repair to just the frames you are going to use in the project, create a new comp from the trimmed footage, then run CAF. When you have the shot fixed, the safest thing to do by far is to render that comp to a suitable Mezzanine format (visually lossless production format video - NOT MP4) then replace it in your comps or NLE for further work. Keeping a CAF layer in a complex composition with a bunch of other shots is just asking for trouble. If the project is fairly simple you could also just nest the CAF comp in another comp.