Fix the AJAX Requests that Make PHP Take Too Long to Respond

In a real-live and productive environment I regard it as obvious to not store sessions in files for many reasons: It's inperformant, it's a security risk, it's not supporting load balancing etc. Once you go with solutions liek database or memcache, you even do not have the above described problem and don't need that solution.

We may have more than one solution but as you mentioned there are many levels of applications and you may don't need to use large solutions but you need to overcome that problem so that solution come to fill that need.