There has been much research done on this:
Wider tyres roll faster off road than skinny ones and the only exception to this is if you are a very light weight rider... I am faster on 1.95's than I am on 2.25 plus tyres as the narrower tyre gets a little more bite.
My riding weight is 140.
Those 2.35's are gonna be sluggish on fire roads and hard pack... especially if the tyre pressure is lower.