Unity lags when importing any 3d object, why?

Well as the tittle say, I have tried importing a few 3d objects in, .3ds, .fbx, .dae and a few more. I have tried with Autodesk 3ds max, google sketchup and a few others.

But every time I import it to the scene it makes the game lag. I even make something similar with Unity, so that I don’t have to import nothing, and then the game don’t lag at all… I made a huge scene with a lot of things in unity and it doesn’t lag.

What am I doing wrong? Do I have to convert any file before importing it? Is there any standard limit for importing a file that I’m missing?

Thanks

If the game lag’s while your import new .3ds, .fbx etc into the project that’s normal. The unity engine needs to process the mesh into unity’s own format but it only does it once (until you need to reimport or change import settings.)

Well I found some kind of solution. So I will post it here in case that anyone have this issue. I scale everything, it take me a while, to a half of the normal size and now there’s no more lag. So maybe it was to big…