My minecraft won't stop crashing

Well every time I go to a world. It crashes on me and even when nothings build in it, and when I go into a server it takes about a minute to crash on me. Please please please fix this. This is might have been suggested a lot. But I'm a HUGE minecraft fan and I always hate bugs on minecraft! But my bugs they do go way in a day or so. Please Mojang fix this. Thank you