I have only had a very brief look at this so far, so I can't really tell you too much about this other than:
- You're quite right, this option is missing.
- This isn't contained specifically to the iPod Classic.
(But I wouldn't blame you for not being aware of that if that's the only target that you have available.)
- It happened somewhere between the 3.13 release and now.
(Which is a hilariously wide scope, but still useful to me or others to narrow this down at a later stage)
- Attempting to re-enable the database RAM cache in git HEAD (the very tip of the development branch) code base results in quite a few errors on undefined references, eventually falling over completely somewhere in tagcache.c
It being disabled certainly looks deliberate, but I have to stress that I have only looked at this for approximately 2 or 3 minutes, so I really can't even guess as to the intention or motivation behind it. I can give it some more serious thought later this evening.