Sheik-It-Easy - Because UAE Center and DXB APP don't sit in the same room, co-ord between the two has to take place via telephone. It takes infinately longer to phone someone up and do some co-ord than it does to just shout it out to the guy next to you. Fixed procedures are put in place to minimize the requirement of co-ord e.g. 250kts at STAR commencement point. In order to go faster one would have to phone and ask for faster. 'Cause APP does not know what ACC is doing and vice versa, the one sector will do something (slow down) to make his picture work. The next sector has a picture of its own and might do something different (speed up) to make his thing happen. So what works for one, does not necessarily work for the other.
If you were to put people in the same room next to each other, this will definately make for a smoother operation, not perfect, but smoother. Add an ATC system that allows for silent co-ord, as opposed to the current mule driven system and things will get even better. Throw in a pinch of flow control (flow, wtf is that?) and this thing might just work. A central flow director for the whole UAE FIR comes to mind. I'm sure I've heard of places that work like that but I can be hallucinating. However, because the people in charge of deciding these things are all bickering, ego driven toddlers, this will never happen.
With the unprecedented growth in the region the good news is that it will get worse.
Edit - Sorry Funky, must have posted at the same time. We should get a life.