I haven't used reflection X, but it looks a lot like some other Terminal Emulators I have used. I had a quick look to see what I could find on it, this seemed to be the most informative page;
I note that the company support version 8 with Windows NT4 Terminal Server, Windows 2000 server and Citrix MetaFrame - can they be pushed for suggestions? I assume your company paid them a lot of money for this product!
QUOTE/
The following issues are resolved in Reflection X 8.0.2:
Reflection X runs correctly on Citrix, Metaframe, and Windows Terminal Server (WTS).
Reflection X now supports Windows 2000/TSE.
/QUOTE
If this is the case, I would expect WRQ to sort it out!
There are some known issues with non-USB key-mappings that have been fixed in 8.06 - have you tried this upgrade?
Further thoughts (Brain Dump);
Since ICA does its own keyboard magic, it could be possible that having more than one session to an app that does its own mapping could disproportionately increase processor load - but that would be tricky to track down unless you had suitable debug tools.
If anything is happening at "DOS" level, then maybe the DOSKBD utility or similar could be used.
If the problem goes away when using a terminal server client, then there is clearly an issue with ICA. Make sure compression is turned off in the clients - this forces more processing on the servers CPU.
ICA depends on the IP protocol - which should be handled by the Operating systems, not the applications. I may be mistaken, but I thought that TCP/IP was a defined suite of protocols which tell the machines how to communicate on the network. ICA delivers to the presentation layer, and Reflection X does its stuff at the application layer - effectively insulated from the protocol.
I had best results with MetaScybe Connect OSI, for plain Terminal Emulation - although it took me a while to sort out the keyboard. For full X-Window support, however, I use MFU! ;-)
I hope at least some of this helps