And as a bonus, I doubled the resolution.
It seems Craftbukkit development has stalled somewhat, which means they’re either relatively satisfied with performance or they’ve been stuck too long. I used last night to do some full renders on all of our worlds at twice the resolution and then turned on active rendering so any blocks you place in the world will update the map after a minute. I also tilted the custom world map to look better, as the location of players there is less important.