When my friends logged-in; It's taking 5 to 7 seconds to show them in my buddylist. But when one of them logout it's taking at most 60 to 80 seconds to remove the user from buddylist.

That is normal.

FreiChat finds if a user went offline by inactivity.
If a user stops requesting the server for certain amount of time, he is logged out.

Thank you for replying adesh.

If a user stops requesting the server for certain amount of time, he is logged out.

Certain amount of time means any exact time period is set. Can we change the that time interval. If yes can you tell me the location.

Thanks.

You can change the offline timeout in the backend -> additional