I've had pretty good experiences with Cache::FileCache. I think it's important to point out that the 'caching-experience' is related to your server setup. Cache::FastMmap is a bad idea if your server is low on RAM, and Cache::FileCache might not that slow if you have a superfast disk-setup (RAID0 with superfast disks for example).

The only way you'll know for sure what will work in your situation is to do some kind of performance analysis of a couple of solutions.