Performance problems in 3Dview

Hi People,
so im modelling one scene and another and now i suddelny have perfrmance problems it’s jerking and lagging very much.
I’ve got an 2,68 Ghz CPU
768mb RAM
Geforce 4200 Ti

and i’m modelling on this blend file

Maybe yu can help me and say what i do wrong because in my opinin it doesn’t seem so complex to need as much suorce to make it unfluid.

Thanks

You have 912216 vertices, and each of your 52 objects have level 5 subsurf. That seems pretty big. From what I can tell, the tear drop meshes only need level 2 subsurf, and the cubes that you made into spheres (you could have used actual spheres), only need subsurf level 3.

Level two subsurf, set smooth, less geometry in the meshes, use edges, creases or edge split modifier to get any needed hard corners.

Thank you very much