Disable Depth Test and Adjust Depth Range
Disable Depth Test if Not Required
If it can be easily predicted that an object is not occluded by other objects then disable depth test (See Render-Mode).
Adjust Depth Range
As the float resolution in depth buffer is highly limited, the depth range should be as small as possible to reduce depth-fighting artifacts. Further, geometry beyond the near and far plane can be discarded in the clipping stage.