Session: Error while trying to free lock for ci_session

@Narf

what about API calls and storing data to Session?
When user logs in app I store his data in session. Because I do not want to call API to fetch user data on every single request specially because users do not change their information very often. Just as example, when user changes the data, call API (before call I need to check is user logged in or not), wait for api, if there is no error in API response update the Session. This is really huge problem with locking. My app have 3 platforms, Android, IOS nad Website.
I can not store data in session immediately after the request like this guy has described it here: http://konrness.com/php5/how-to-prevent-...-requests/
Our app is on AWS, have 5 servers behind ELB and using memcached for sessions.
I am trying to fix this for 3 days with no success.
Added session_write_close() after set_userdata call but still 5s response time.
I hope it is clear, now.
Maybe BUT maybe I am doing something wrong or this is total mess up.