float[] → Vertex[] – decreases performance by 1000%

[David]

> This is strange. You said that you profiled the program and the extra
> time spent is not in user code? Where is it spent then?

This is a damn good question. I tried to debug it manually with 
writefln's, it showed that glfwSwapBuffers needed the time (which, I 
looked it up, is just a wrapper around glXSwapBuffers). `perf` showed me 
nothing, the time was used in some unresolved calls.

I will make new tests with perf tomorrow.