I've been profiling my application lately, and I got something weird, which I hope one of you can explain to me.
In my Scene, I have a large World-Mesh and about 5000 decoration Objects, which all are using the same PixelShader, which simply does one Texture-Lookup. All in all, I get about 1000 Drawcalls from this and about 105fps on my laptop. There are no post process effects or similar techniques.
The weird thing is, when I switch to a very simple PixelShader (Using Intel GPA), my FPS-Counter ramps up to ~150, even when there are next to no pixels at all drawn on screen! (Small health-bar in the corner, but thats it).
Applying a 1x1 scissor-rect doesn't give the same effect.
How can switching a pixelshader improve performance by so much, when there aren't even any rendered pixels on screen?
Thanks in advance!