The "Export Progress, Writing Entities" bar won't even move. My model isn't overly complicated or overly intricate. I haven't had a problem with it being slow while modeling. What's going on?

The shadows flicker, move and make incorrect geometries in my exported animation. Why does this happen? How can I correct it? Thanks!

I know this has to do with the geometry of the model being too intense or too much, but how do I eliminate the wierd section looking view without sacraficing my model? I want to make an animation but this phenomenon also shows up on the animation...