session_start seems to be very slow (but only sometimes)

Question

For some odd reason, just today our server decided to be very slow during the starting of sessions. For every session_start, the server either times out after 30 seconds, or

Answer 1

Each session is stored by apache as a text file.

When session start is use to resume an existing session (via cookie identifier for example) maybe a big session file (a Session with a lot of content inside) can be slow to be started?

If this is the case probably you application is putting to much data into sessions.