I have a MASSIVE square of water on my superflat world, made in a much older version using MCEdit. When I try to map my world, the map makes the game drop FPS, then eventually become completely unresponsive when trying to map that part of the world. The rest of the world is fine. Also, by unresponsive I mean I can't do anything, but the game is running fine.
Is this still a concern in the current Minecraft Snapshot 15w44b or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Does this happen too with natural generated water ? Deep ocean ?
Does MCEdit generate flowing water or source blocks ?