Quote - My experience is that render times are less in 4.6 than they were in 4.5 for the same scene and lighting.

Render times depend a lot on how you do the lighting and how much transparency is used in the scene. Some hair can slow down rendering a lot. Some other objects with a lot of transparency can slow do your render.

How are you doing lighting? What is in the scene?

My experiences of going from 4.5 to 4.6  match yours. Render times are noticably faster. I've also found that long, thick hair slows down the render.