It shouldn't be slower because you're running the same programs on the same hardware. If anything, AR has the advantage of rendering only AROs instead of full Matrix sculpting and reality filters. It also doesn't need to process biofeedback. If your commlink can't keep up with AR, then how can it keep up with VR?
The machine (computer) can act fast, but the AR-Interface isn't designed for fast use. At least not as fast as superhuman (2+ IP). But there is another argument on my plate. See drones and there autonomic control, they act in 3 IP not faster. And a even better argument is the remote control (that is what AR is for me in compared to VR) and look and behold the interface change simple actions in complex actions.
Just to repeat I thing the computer itself is fast enough but not the interface control of a AR, it is designed for normal common people use, not for superhumans.
Frankly, I don't see why VR should have an advantage over AR anyway. For the people who can take full advantage of it, AR is simply newer and better technology. It's like running wireless instead of wired: Other than some special applications, there's not much need to do things the old-school way.
The VR-Technology doesn't stay still, it evolves too, even after 30 years of market maturity. So it is long time there, but it's faster and better designed this days as ever before. And it's still the directly way "brain to machine"-technology without a detours over body movement and "simple for everyone"-interfaces.
AR is simple a mash up or melting technology it has to work with the physical world and so it is limited by that world and their beings (nearly all of them work on 1 IP base) and its design is a mass product so it comes from a average norm (and like I said, the norm is 1 IP), so why should it be faster then that? After all there is a well-established technology that improves the working speed and is called VR.
Do you get my point?

Only to say it again, for me it isn't about character types that benefit from that rules it is more the question about technology and logical and functional interaction between the background (world description) and rules to representing that.
And to talk old-school AR is that equivalent to snails systems of the past, only that their rule base turned out to be much faster plus all the snails advantages. And that couldn't be the RAI behind that.
I have nothing against the meat speed idea, at all. But it should be in any case slower then VR speed or it should have some disadvantages that makes it more difficult (or dangerous) to use. A good start would be that the simple action become a complex action, like remote control.
Even the old rules (SR4) had a regulation (but it was a terrible one; I speak of the different searching Interval), so they tried to regulate this in a bad way, ok. But the need to regulate and balance that problem is not a bad idea, only the chosen way was.