The same file, opened / rendered in 2.8
and opened / rendered in 2.79
First test was with slightly different settings, HDRi map was rotated to 90 degrees, and image size was 5000x5000
All shaders are procedural with translucent etc.
After that I just opened the same file in both blenders, decrease image size to 3000x3000 to reduce render time:
2.79 - 12m 20sec
2.8 - 17m 56sec