I can create a world, log into it, and fly around to my heart's content with no out of the ordinary framerate issues. I've been scoping out terrain in many new worlds by finding an interesting area in creative, then trying to make maps of it. I produce anywhere from five to ten maps of different chunks and make a wall of glowing item frames to post them on. As I create more maps the framerate drops dramatically, eventually reaching zero before the game freezes (not responding) and crashes with Exit Code: 0. At first I though it was a one time glitch, but I've noticed that it happens every single time once I get to a certain point of mapping my surroundings.