Does SketchUp models take extra performance?

I’ve imported some 11 sketchup models, and the performance is very bad, am I doing something wrong? I’m using the free version of sketchup and unity. So I can only export the .dae file type

SketchUp models are represented in the same way any other model is represented. The main problem with them is that they are primarily used for Architectural representations and other rendering applications which can be tolerant of highly detailed models.

Where did you get these models from? If you observe the models and their vertex/polygon counts you might find that many of the ones from the warehouse are pretty highly detailed and as such unsuitable for games. In this case you need to try and remove as much of the excess detail from the mesh as possible.

One time I imported a 3D building into a scene with an insane amount of vertices and it killed performance, turned out there was a book shelf in the basement and each of the books had several thousand vertices alone.

As for filetype, you can export the file to Blender and then export again in whichever file type you prefer.

Well you have to keep in mind that sketch up uses two-sided faces for it’s models. So you can, when you export the models go on advanced and deactivate the two-sided faces. But when doing this you will often see, that the normal is pointing the wrong way, so you will have to fix that in another application like blender or maya.

I have also realized that sketch up tends to create multiple materials, if you are using the same texture with a different scale, as the UV system of Sketchup isn’t that great.

This are both performance killers. Especially the first as it results in having twice as much triangles in the scene.