Closing server when index becomes very large is slow

Not sure if I would call this a bug, but when the index gets very large and the server is closed the `sdump` function takes a very long time causing the server to look like its hanging.

A quick improvement would be to create a message stating that Fist is attempting to `Exit cleanly` before sdump is run, but there is a deeper problem to be solved here so that's why I am opening this issue.