It seems that the longest waits in start up time are after
openlp.core.ui.media.init DEBUG get_media_players<br>
However, there isn't always a delay, only when doing work with the controller. I can't see anything in get_media_players that could take along time to process. However the log entries after the instances of get_media_players seem to do with the initialization of controllers.
This leads me to guess that the issue is something to do with one of the media players. Which ones do you have selected? Try disabling the vlc backend (my guess as to the culprit) and restarting OpenLP.