Is it make a sense to build embree accel structs in world space and convert rays/poinrs from camera to world before cast rays? Many scenes are built as "more aligned" in world space. so at least in theory a better data ballance/division can be achieved. Did anyone try and what is an effect?
In ray tracing you by default build your acceleration structure in world space, to take advantage of aligned geometry as you point out. This further has the advantage that one can move the camera without having to rebuild the acceleration structure. To get best performance pass world space geometry to Embree.
Your camera view is almost axis aligned, thus it is not surprising that you do not see a big difference. If you rotate the camera by 45° you should see a performance degragation.