It does seem like earlier levels make it much easier to mine points. You're not as punished for hitting the big planets repeatedly, and the open space invites you to play around a lot more. Levels 8 and 10 feel very compromised until you get the mouse issues fixed. They force you to mostly shoot in one direction and it really limits how much you can experiment with until it's just time to go straight for the target to close out the level. I would maybe think about adjusting the configurations of the objects in those levels and spread them out more - you want levels that feel engaging and open, not levels that force you into one play style.