1) You need to limit spring's length or it explode on zoom out and move mouse far away (same with wheels).
2) Instead of using lasers and scene.my. variables you can bind mouse_left directly to claw's hinges with "trigger" option.
Same can be done with no hinge - just set "followGeometry" property of thruster to false. And you don't need any lasers at all (even if you don't want to use readable, one laser is enough)
Bill, Gent. ATI cards really lag in algodoo (because of bad openGL optimization I believe). geForce, even old one like 8600GT much faster in that case.