FreeSwitch Simplest configuration -

i've installed freeswitch , managed , running on centos 6. can connect instance using sip application (x-lite) , make calls between extensions.
i've done used out of box default configuration seems me default configuration purpose.
want instance connect internal extensions, there no calling outside, there no real dial plans, simplest of all. able different extensions call each other, not voice mail required.
wondering if there simplest configuration can use. reason need default configuration not fast enough , when extension makes call next takes around 5 seconds before heard ringing , hoping disabling features don't need can make process faster.

so question is:
1) there bare bone simplest configuration can use?
2) cause of delay see in configuration or there might other reasons?

again remember out of box installation, i've done checked out code , built code , run instance.

thanks in advance.

see here: https://github.com/voxserv/freeswitch_conf_minimal/blob/tutorials/docs/tutorial_01_simple_pbx.md

this tutorial based on minimal configuration available in same git repository. feel free use own purposes.