Well Superman was a big jerk in the movie. And ya know so very full of himself. I mean come on he waited around to get the credit for everything he did, so not superman. And the kryptonite parts were totally off. Even the smallest piece being near superman totally negates his powers so there's no way he could have been able to lift that thing laced with kryptonite. And yeah it was way to long. I so dislike the superman character in this movie.
Well we never see a tiny piece of Kryptonite near Superman in the movies. You have to leave the comics out of it. None of these comic book movies ever hold true to the comic story lines. What we do see however is that Superman struggled to get that rock mass off the Earth. We also see him tumble to the Earth because of that tiny shard being inside of him. So....I think you're making a big deal out of nothing. And Brandon Routh was a pretty good clone of Christopher Reeve.
don't forget he supercharged from the sun right before he dove way underneath the rockmass. he probably had a nice barrier or seabed between him and the kryptonite. as the kryptonite got closer to him, he was further out into space where the rockmass became lighter and lighter...