I’ve just installed Unity 5 and opened my 4.6 project in it, which is a 2D game. And for some reason the player starts moving up very slowly, as if there was some force on it. I didn’t make any changes to the project, just opened it on 5. And I already tested it on the older version, it still works fine.
This happens to me when I have Root Motion enabled on the Animator.
In actual fact, it happened in 4.6 even before I converted my project.
There must be a small difference in Y between frames of the animation.
Baking Y will probably solve this.