There was an oversight in an earlier version of ACR where a certain functionality was not supported in AMD machines, but that oversight was very quickly corrected. I don't even remember exactly what it was, but it's nothing to be concerned about now.
Should add the question, does having the fastest processor really matter? Bridge is more processor dependant, but Photoshop is more RAM dependant. Then you have the other programs to consider also. But even so, will you see any difference? Depends how much stress you put it to. For the normal user I would guess you would never see it. You have to weigh the cost of increased processor speed with your expected gain.
My CPU was a middle choice 2 years ago. Probably slow by todays standards but have no complaints. The Passmark rank is 5004.