I ran into a MAJOR problem with this disk cache file issue, to the extent that I would call it a bug.
I began my process in Adobe Premiere, editing almost 3TB of footage, and set up my SSD with the disk cache file directory, as specified by Adobe. Then, I continued my process in After Effects, where it automatically uses the same cache directory specified in Premiere.
The problem started happening in After Effects, when EVERY time I would save, the system would save properly, but then when I clicked the mouse to begin working again, the beachball (Mac OS X Mountain Lion) would spin for nearly 2 MINUTES (I timed it). This happened every single time I would save!
I tried EVERYTHING from disabling multi-processing, to re-allocating RAM and CPUs, etc. until FINALLY I decided to point the cache directory to a new, fresh directory on my SSD, and “deleting” the old cache when it asked me to. Ta-DA! Problem solved, everything runs perfectly now!!
Bottom line, when using a large amount of media, the cache file directory can balloon to a huge unmanageable size that causes After Effects to hang. Surprisingly, this hangup does not happen in Premiere.
WHY IS THIS VALUABLE BIT OF INFORMATION NOWHERE TO BE FOUND FROM ADOBE?!