stunt-kerbal

whenever i buld a BIG craft,it always fall. normaly ,you just add more strut, but my computer just doesn't like strut, and lag REAL BAD if i add many struts, so does anyone know how to build a big ship without using many struts? or just some building tip, because i can build spacecraft that can travel to mun, minmus, but not other planets, like EVE ore Duna. Please help P/S how do you switch the forum layout, i accidently click on the Switch Layout button and now it's look like something you would see on a Iphone or something.