I don\'t think it\'s clear to me yet, is it faster to read things from a file or from memcached? Why?
There are quite a few different aspects that might favour one or the other:
I would suggest you look at your use case and do some profiling of both approaches. If you can get away with using the filesystem then I would. Adding in memcached adds in another layer of complexity and potential points of failure (memcached client/server).
For what it's worth the other comments about disk vs memory performance might well be academic as if the filesystem data is being accessed regularly then it'll likely be sitting in OS or disk cache memory anyway.