When a long 70 mile course is loaded it slows the map drawing time to 2-3 minutes during which time the white map page is unresponsive until the map details are drawn. Then seemingly randomly a right turn is indicated while the map shows a left turn is coming up. Then a U turn is indicated when the map shows the course ahead to be a straight road.
The map drawing speed improves to the same speed as when no course is being followed when there is only a few miles left on the course.
The map feature to route to the start while following a course is not usable as it never routes the best course back to start when other than follow existing route is selected.
It is clear why other manufacturers of similar bike computers can successfully compete against Garmin bike computers