I have an RDS server physical on Dell PowerEdge T410, 16 cores, 32Gb RAM.
With 8-10 RDP sessions connected only 5Gb of physical RAM is used out of the 32Gb available. The apps (Dynamics ERP) are performing sluggishly - at least 50% slower than in native Windows client server on an average desktop. The desktops utilize 2-4Gb each, so I am having hard time understanding how 8 concurrent sessions only uses 5Gb. These session should be faster than on desktops. LAN/WAN bandwidth is not in the picture, because the same slow speed happens on the console.
Note: in addition to RDS, this server also has IIS Role.
Maybe the server is not tuned for RDS?