As my title already suggests I am having a little bit of a weird problem. First of all let me show you a picture of what im talking about.
This is how the scene normally looks right now:
Currently there is virtually no optimization, just frustum culling and "not-rendering" of invisible blocks. As you can see it renders with over 250 FPS. However if I turn 90° to the left, watch what happens:
There are less triangles rendered (indices/3) and also fewer draw calls in the second image, but the frame time nearly doubled. I am baffled why this happens. The geometry is exactly the same, the exact same rendering setup, same shaders, there is no branching in the shaders that might only happen in the second picture. Its also not depending on the light direction, when i invert the light direction so that the first image in the situation above gets hit by specular light and the second is that dull gray its the same effect. The maps are also generated randomly at each start, so this also can be ruled out.
I really wonder what could cause that issue, does anyone of you have an idea what i should start checking? I already did a lot of CPU profiling where i spend a lot of time in either of the two situations and compare the render loop for changes, but so far i havent had any luck. Could it be something on the GPU? Even if everything is pretty much identical?
Thanks in advance,