If it's more efficient? Hell yeah. Also, say you end up with memcached, or redis, why not cache session data in it so you don't need to query the database or t

If it's more efficient? Hell yeah. Also, say you end up with memcached, or redis, why not cache session data in it so you don't need to query the database or the fs, etc.. Usually there are a lot of things to put into a cache. And memory is always faster than disk. But that's all assuming you really need it. I wouldn't throw anything new at an app when it's not necessary. You need to know that yourself.