I have a brand new Mac Mini, configured with Intel i7, 16GB, dual SSDs... basically the top of the line Mac Mini you can buy as of 2/1/2014. I also purchased the latest Airport Extreme, with 802.11ac and I'm connecting to my Mac Mini with the greatest and latest MacBook Pro, which also has an 802.11ac.
For some reason, when I use screen share to connect to my Mac Mini from my MacBook Pro (through the Airport Extreme), the screen redraws very slowly, the mouse pointer tracks very slowly, and the whole experience is just sluggish even at 1280x1024.
Just before I upgraded to the Mac Mini, I had the same setup with the previous generation Airport Extreme, and a 27" Intel i5 iMac. When I connected with my MacBook at native 27" display resolution, the response was very fast and snappy.
How could I possibly have a faster computer and network and have terrible screen share performance?
As a side note (not sure if this is related), I run Windows 2012 Server in Parallels on that same Mac Mini, when I connect to is via Remote Desktop Connection, I have the same problem. Again, the previous generation setup (Windows 2008 on the older Airport Extreme and i5 iMac) worked far faster.
The CPU and memory is idle 99% of the time on the Mac Mini.