I don't think so. 46 will be slightly faster. But really how often do you use your big ring? I found I never use mine so I replaced it with a bash ring. That may be the reason for my answer. Please note you may need a longer chain if your switching to the 46
I use the big ring all the time because I ride on the road and very light trails at the moment.
You may be scratching your head wondering why I bought a mountain bike instead of a street bike right now - so I will answer that:
I have been suffering from chronic lower back pains due to my work and it was advised that I started to exercise and bicycling was one of the things that was mentioned.
Since I live in the Netherlands, most of the roads are brick - which happen to be uneven due to the heavy construction & delivery trucks that use them on a regular basis.
I ended up getting a full suspension bicycle to help take the beating out of what I would be going through with a hardtail since the bulk of the damage was done when I was in my early 20's and was too stupid (and poor) to let everything heal properly in the first place.