Yes Shu, I know, it remains weird. It appears, just a wild guess, that it handles not just the data shown on the screen, but maybe a whole map tile (or 2) involved. Or something like that. Istanbul is 5 times as large as Madrid, so maybe the CX deals with a whole lot more map data there besides what is shown on the screen when zooming and panning. So in Istanbul it was possibly trying to juggle the whole city of 15 mil people when zooming / panning. The trouble I had in Istanbul applied to OSM as well as Garmin maps, which leads me to believe it is a CX / data quantity issue, not a map brand issue.