A low polygon sphere for the planets I noticed a change in speed
don't use it if your card is the best. Its rather ugly
but you can play with Nvidia GeForce FX 5200 much better.
Instructions:
1. delete a file named "sphere.x" in the models directory.
2. doownload the this file: WWW Link

quite useless but maybe useful for people who care about speed.
next time I'll upload better things.