So I have vague information on this. Some friends of mine who have this game have a mod for it that makes the textures look more sexy or something. Extra details, more refined, but still staying with the look and feel of traditional MineCraft. Now as far as I know it's a mod, or it could very well be directly related to the recent updates I only vaguely remember hearing about.
Either way, the work around for that was going into Java and telling it that it was allowed to allocate more RAM beyond the default setting of something like 256mb. Again, not entirely sure. In fact all of my information could possibly be related to nothing at all!