The map's cache will be getting wiped early this week in order for them to display the new NPC screenshots. This may make them load slowly if you're the first one to view a zone. If a specific zone loads slow once, that's expected, if it continually loads slow there's a problem.

I'm pre-caching the NPC screenshots now. Because of the way the map loads the screenshots--on the fly--it would otherwise be really frustrating to wait for a few seconds for every NPC popup to display. As soon as the images are done caching, I'll wipe the map cache. That should trigger the maps to use the new popup/images.