So if you check the help, there's a bajillion encoders and decoders listed that one can enable. Annoyingly, there's not an --enable-all-decoders option, so I ended up with a ridiculously long config line when I added all of them. (Why not was roughly the reasoning.)
Successfully compiled, zoneminder's working fine with it, I'm wondering if making it so fat will cause any performance issues. Having nuked the old install, I can't easily make a comparison of it's performance.
Ffmpeg compile with extra encoders/decoders
I am no ffmpeg expert, have only done minimal work in the source code myself, but the short answer (and my 2 cents) I would say is no. Once a specific encoder/decoders is selected ffmpeg doesn't really need to spend any time in any of the other encoder/decoder code so while your binary and dependencies and even possibly initial startup time may be larger actually encoding/decoding time really should not be effected.