Basically if you change any of the Mantis related settings (e.g. server path), the settings dialog waits for 10 seconds. Then if you don't do any more changes, it rechecks the new settings and reloads all important data from the server. You should be able to see the behaviour by looking at the right side question mark icons. They turn activate 10 seconds after you did the last change.
Originally I tested changes much quicker than 10 seconds, but that caused some problems (I don't remember which problems exactly), so I changed it to 10 seconds.