Meshperformance

I have 49 meshes with 2048 faces each.
Each mesh got one surface.
If I render all of them I get a framerate of 50 Fps.
Now, I if clear all the triangles in every mesh, the meshes ain't visible anymore yet I only get a framerate of 120 FPS.
Why is that?

Even if a mesh contains 100000 vertices and 1 face that uses 3 of those vertices, the rest of the unused vertices shouldn't affect the rendering performance, or would they?

Not rendering performance, but processing will take some time anyway. The frame rate isn't just rendering. Try timing the RenderWorld command on its own.

But why would the amount of vertices affect the "internal" blitz3d process? In what way are the vertices used when no triangles are defined?
Or is it the 49 surfaces that causes this "slowdown" and not the vertices at all?

It would be the 49 surfaces. Many surfaces can cause a slow down in Blitz merely on their own. Like MasterBeaker said, there is processing time and even though the surfaces are not rendered, they are still there and there must be a certain amount of processing that must be done for things like Zordering, entities, etc...

well depending upon how blitz works, it is proberably still transfering all of the vertices across the system bus. this would lead to slower performance