When deploying RemoteFX, we found several settings that had to be tweaked in order to achieve usable performance. I have found some of this information is not really talked about in the documentation.
First, it is important to set Power settings both in BIOS of the Hyper-V host, to Max Performance. It is also a good idea, to set the Power Settings in Windows to Performance as well. (Windows can control some BIOS power settings depending on how to BIOS is configured, but I still find it is better to simple set both to Max Performance in RemoteFX systems).
Secondly, do not use the Legacy NIC with the RemoteFX adapter. We found huge amounts of lag when using RemoteFX and the Legacy NIC. If you need legacy NIC for PXE, it is recommended to switch to the standard NIC once the machine is ready for production.
Hopefully these two things will help you see performance improvements in your RemoteFX VDI environments. In our case, performance was about 10x better according to graphical benchmark tests.