A couple of years ago, Sam Skillman (email chain attached) asked about support for saving derived fields to the disk, so we don't have to re-compute expensive fields over and over again. Did this functionality ever make it into yt? I'm working on something where this would be very useful, so if not I might have a go at implementing myself.
I've started dealing with a lot of time-consuming derived fields and am wondering if there is already support for writing derived fields back to the raw data files (e.g. .cpu files). If not, any thoughts on doing so?