Using a High DPI mouse (such as the Roccat Kone Pure) - causes severe performance problems when using Horizon.
The performance is comparable to (and compounds) the issues described here and here
I can replicate this behaviour on both Windows and Mac.
The issue is most prevalent when using MobaXterm as a published application, but is still evident with other applications.
You will observe extremely laggy mouse pointer movement, trailing by up-to 45 seconds.
The only solution is to use a standard mouse or trackpad device.
The Mac client is still subject to out-of-order processing of mouse events (as described in the threads linked above).
The Windows client is less problematic regarding the ordering of input events - however the performance remains terribly bad.
In order to illustrate just how bad the out-of-order processing is on a mac... when the lag is at its worst, I can move away from the Horizon applications and interact with native applications on my desktop - and yet still observe my clicks (in a native window) being processed and interpreted by Horizon in one of its windows. In effect, the click event is being captured at the position my mouse was at 45-seconds ago. It's incredibly disconcerting to interact with a native window and see Horizon responding to it in some other window that doesn't even have focus anymore.
Mac: Horizon Client 4.6.0
Windows: Horizon Client 4.6.1