I've gotta say that I did have mini-freezes in DX11 and I have a very capable PC to run AH with.  When I tried using the DX9 version I did not have mini-freezes.
It's not the connection.  Connection same playing both versions.  Mini-Freezes just disappeared when using DX9 which I use 100% of the time now.  May have 
something involved with the use of 3D Glasses which I understand the DX11 ver. is constructed to do.  Just an uneducated guess on my part.