Huge lifesaver feature, I have been waiting for this kind of feature for a long time.
really amazing guys... just like Peter said, well done and thank you.
Here is my comparison in a real-world scene that I have been working on to test the new feature in the real-world situation...
I have tested Corona 4 with old displacement with and without Auto Bump in comparison with Corona 5 with 2.5D new displacement with and without Auto Bump feature...
I have set a noise level limit of 5.0 to all tests so I can compare the render time.
in Corona 4 with 0.5px I have got low on ram(I have got 64GB Ram on my system) warning both with and without the auto bump. and render time was near with auto bump it was 38min and without it 33min.
in Corona 5 I have no issue with ram in any way... huge step up. and parsing time was actually decreased which is awesome.