Could be that your structs are getting default initialised so you will
be getting a constructor called for every instance of a Vertex.
This will be a lot slower than a float array.
Try void initialising your Vertex arrays.
http://dlang.org/declaration.html
See the bit Void Initializations near the bottom.
Also make sure that you are passing fixed size arrays by reference.
No. The vertices are just created once (with a call to the default ctor)
and immedialty added to the Vertex* but they are never instantiated.
