Alright, I've had a 'rash' of weird issues and they all seem to involve the RB112... It may be software, or power, or maybe capacitor failure. Basically they get very slow - less than 2mbit/sec throughput, extremely long waiting times for the prompt to show up in terminal, takes forever for interfaces to list when logging in with winbox, etc etc.
Usually the CPU will linger between 15% and 80%. Under much load it'll show 99% or 100%. They seem to act a LOT happier if all the wifi is disabled (idle down to 1-2% cpu, 35mbit+ on a one-way bandwidth test). Yes, adaptive interference stuff is disabled (it munches CPU on the 100-series)
Now, most of these had been upgraded to 3.x (95% of my clients are at 3.10 and 3.11) and modern copies of routerboot so I'm not sure if its a version-bloat issue or what. My APs are all 3.10 and 3.11, and seem to hate 2.9 now, so downgrading isn't a good option.
So far, I have only seen this on the 112, and we have considerably more 133/133c3's than we do 112's. Is the Ram/Flash/etc especially slow on the 112? Is there a suggested way to get them to 'act right' again?