[ Warning excessive nerdiness follows. ] Since you're curious, Garmin's GGZ and observation of the units behaviour offers a pretty good hint on why this has been a problem with dozens of Garmin models. I've not reverse engineered them to confirm this and I could be wrong, but I have a bit of relevant engineering experience here.   If you add a big GPX file and boot, you'll notice it takes a long time. Some combination of the XML parsing and putting into the unit's internal (probably sqlite3) d