Almost one year ago, after a long co-development with the startup Teradici, VMware launched a software-only version of the remote desktop protocol PC over IP (PCoIP). PCoIP support has been introduced in View 4.0, side by side with support for Microsoft RDP, and it’s obviously still present in the new View 4.5.
Since then, customers interested in VDI have wondered if PCoIP is on par or superior to the Citrix High Definition eXperience (HDX) protocol, an extension of the ICA protocol, introduced with XenDesktop 3.0 in February 2009.

While a few benchmarks have been published about the topic, there’s a lack of real-world tests that can answer the simple question: how the experience will be for the average employee?

Chris Wolf, Vice President of Research at Gartner, just provided an answer: the two protocols are on par on LAN, while Citrix HDX performs better over WAN links with more than 200ms latency.
Wolf tested both XenDesktop 4.0 Service Pack 1 and VMware View 4.5, through a L2TP/IPsec VPN to connect from Europe to his facility in US.

The test itself is relatively simple. I connect to the XenDesktop and View environments one-at-a-time and perform a few basic tasks. After connecting, I open a Word document and add a comment. After that, I open a browser-based Flash application (imaginationcubed), watch the sample drawing, and then use the app to write the word “hello.” Each test lasts from just over one minute to three minutes, depending on the speed of the network I was on at the time.

The tests have been video recorded (part 1, part 2, part 3 and part 4) and the verdict is clear:

I found that as latency increased beyond 200 ms, ICA/HDX had a decided advantage over PCoIP. Text entry and menu response with ICA/HDX was still good enough to keep me productive, while the PCoIP response hampered productivity. When latency was relatively low (e.g., under 120 ms) both protocols performed well enough to meet my expectations. At several locations (i.e., Newark Airport, Munich, and Copenhagen) both protocols were able to deliver a good user experience.

Even if the test he performed is not a rigorous benchmark, Wolf earned well-deserved credibility in the virtualization industry over the years, and the market will certainly pay attention.

http://virtualization.info/en/news/2010/10/citrix-hdx-better-than-vmware-pcoip-over-wan-says-gartner.html