Why Reflection Detail works great on city lights...

Question

... but poorly on runway lights?

Whatever the plane I use, when the fuselage shows some reflection, there is no problem with city/scenery lights even on my old 2011 iMac. Example here at 1:00 https://youtu.be/q3p2MRXW0Xg?t=1m as city lights reflect on the fuselage of the B777.

But when Reflection Detail is enabled with the cursor on the right side, there is a strong delay and the reflection is blurry with the lights of the runway.

I tested the same situation on a brand new iMac with a very powerful GPU and even there the Reflection Detail is late and has a lower FPS than the rest of the scene.

So, why Reflection Detail is poor with runway lights and not with city lights, and why is it slow even with a powerful GPU?

I just hope that one day in X-Plane we will have this kind of reflection: https://www.youtube.com/watch?v=E4aMVFT0Jak

Comments

And as you can see at the beginning of my B777 video where the planes are taking-off, I had to remove the Reflection Detail otherwise it will be visible with a very low FPS compared to the rest of the scene that is smooth, that would have been totally odd and unesthetical.