session_support
This controls whether vsftpd attempts to maintain sessions for logins. If vsftpd is maintaining sessions, it will try and update utmp and wtmp. It will also open a pam_session if using PAM to authenticate, and only close this upon logout.
You may wish to disable this if you do not need session logging, and you wish to give vsftpd more opportunity to run with less processes and / or less privilege.
NOTE - utmp and wtmp support is only provided with PAM enabled builds.
default=NO