There is an ongoing battle for dominance in the virtualization field, and lines are being drawn. Whose side are you on? Myself, being a VMware evangelist, I obviously side with VMware. That being said, I don’t feel as if I am offering a biased opinion. I’ve been to Citrix’s Maryland headquarters in Bethesda, and they gave me a well thought out demo and really impressed me with some of their features. I was specifically going on a work assignment to evaluate their VDI solution offering, XenDesktop. While I was there, they also gave me a thorough education on their hypervisor offering, XenServer. Both products are very pleasing to the eye, with rich graphics, given their use of the HDX technology that delivers amazing crisp desktop images. We actually are in the process of deploying a 10 seat VDI test environment using their XenDesktop solution, and thus far there have been no problems. I don’t want to get into brand bashing, I’m not into that, even as much as I love VMware and the software they provide, I still respect Citrix and their forge into the virtualization market. I want to present this argument with the highest level of objectivity I can offer it. With that in mind, please read this post with an objective mind, and judge for yourself. Which solution is better? VMware may not be suitable for your needs, while Citrix fits, and vice versa. Let’s be objective and logical in our reasoning for choosing a solution, I assure you with that approach you will never make the wrong decision based on your goals.

Back in 2009, Citrix CTO Simon Crosby and VMware Technical Marketing Manager Scott Drummonds debated virtualization/hypervisor performance. This event was held at the Burton Group Catalyst Conference North America 2009 and was moderated by Chris Wolf. This is a year old but I think the arguments remain the same. Have a look at the video and see who you think comes away with the most compelling argument. Some of the main points of debate were focused on technical nuances that offer the greatest performance benefit/detriment to VMware and Xen hypervisors, effective methods for measuring hypervisor performance and the potential barriers to perfomance scalability.

What does each company bring to the table?:

VMware, the global leader in virtualization and cloud infrastructure, delivers customer-proven solutions that significantly reduce IT complexity and enable more flexible, agile service delivery. VMware accelerates an organization’s transition to cloud computing, while preserving existing IT investments and enabling more efficient, agile service delivery without compromising control. With more than 190,000 customers and 25,000 partners, VMware helps organizations of all sizes lower costs, preserve freedom of choice and energize business through IT while saving energy—financial, human and the Earth’s. VMware delivers virtualization and cloud infrastructure solutions that enable IT organizations to energize businesses of all sizes. With the industry leading virtualization platform – VMware vSphere™ – customers rely on VMware to reduce capital and operating expenses, improve agility, ensure business continuity, strengthen security and go green. With 2009 revenues of $2 billion, more than 190,000 customers and 25,000 partners, VMware is the leader in virtualization which consistently ranks as a top priority among CIOs. VMware is headquartered in Silicon Valley with offices throughout the world and can be found online at (taken from

Highlighted products include:
VMware vSphere Hypervisor (ESXi), VMware vCenter: Server, Lab Manager, Converter, Site Recovery Manager, VMware vSphere, VMware View, VMware Workstation

Citrix Systems was born from the idea of unlocking applications from datacenters, and employees from the office – changing the way IT and people work. Today, this is the promise of virtual computing, and Citrix is at the epicenter. In the world ahead, the better way to work is virtual – completely untethered from the office, devices, networks and datacenters. This virtual workstyle creates new possibilities for personal efficiency and business speed. The world’s smartest organizations are discovering that “going virtual” is how to stay ahead in a business world that’s changing faster than ever. Virtualization goes far beyond just consolidating servers. It’s also about powering the cloud, enabling online collaboration from anywhere, and taking desktop computing to an entirely new level. It’s about elevating IT from managing equipment and systems, to enabling them to deliver computing as an on-demand service. For our customers, it’s about unleashing the productivity and creativity of people, allowing them to seize business opportunity ahead of competitors. By applying our virtual computing vision to everything from meetings to desktops, networks and clouds, computing can be far simpler. Our belief in the power of simplicity becomes more market-relevant every day and is the basis for how Citrix will continue to drive long-term value for shareholders, employees, customers and partners.

Highlighted products include:
XenDesktop, XenApp, XenServer, Citrix Receiver and Dazzle, Go ToMyPC, Citrix Essentials for Hyper-V

Both VMware and Citrix present valid arguments as to why they should be chosen based completely on the information, products, and statements shown above. Let’s dig a little deeper though. With the recent release of VMware View 4.5, and the flood of entrants into the desktop virtualization field, I’ve chosen to focus on each company’s desktop virtualization solution, VMware View 4.0 and Citrix XenDesktop 4.0 (with all fairness to Citrix, I’ll be comparing View 4.0 to XenDesktop 4.0).

First up to bat, Citrix. In February of 2010, Citrix commissioned Miercom to evaluate the effectiveness of two similarly configured VDI solutions using XenDesktop 4 and Vmware View 4. Let’s first take a look at the configuration Miercom used to base their validation on:

    *2 HPDL360 servers w/ 2 Intel Xeon Quad Core processors
    *Each server had 12GB of RAM & 3x72GB disk drives for installing XenDesktop 4 and VMware View 4 suite for testing
    *XenDesktop 4 server loaded w/ XenServer v., Service Console 3.0, Dekstop Delivery Controller v. 4.0, Virtual Desktop Agent 4.0.4522, Virtual Desktop Client
    *VMware View 4 server loaded w/ ViewConnection Server 4.0.0-210399, ViewAgent 4.0.0-210939 and ViewClient w/ offline 4.0.0-210939

How was it done? This is an excerpt from the report on the research was conducted given the equipment listed above:

We connected two servers to the Apposite WAN emulator through a switch.We used an Apposite WAN emulator for bandwidth restriction and to introduce packet loss and latency to the network to simulate remote user connections and constricted WAN environments. We also used Login Consultants VSI script that helped automate
the launch of Microsoft applications including Excel, Word and Outlook in a consistent manner while measuring CPU and bandwidth utilization. We used the ClearSight Network Analyzer in our test bed to analyze the efficiency of the application protocols used: ICA with HDX for Citrix and PCoIP for VMware. We utilized Video Clarity ClearView systems to determine VidMOS scores for quantitative analysis. Each server was equipped with a domain controller, DNS, connection server and broker as the part of the
virtualization platform. We measured bandwidth utilization and assessed the Quality of Experience (QoE) while playing Flash movies accessed through Internet Explorer 8 from websites including and, using the virtual desktop software installed on each client. We used an Ixia XM2 chassis to apply IMIX background traffic while capturing the Flash
video content for analysis. Real-world traffic was also used in testing as generated by Ixia’s test platform and test applications, principally IxNetwork for Layer 2-3 routing and switching traffic and IxLoad for Layer 4-7 application traffic.

The results were actually pretty shocking to me. While accessing applications like MS Word, Excel and Powerpoint, Citrix XenDesktop used only .377Mbps while VMware View used 1.029Mbps. That is 64% less bandwidth usage by XenDesktop! That is pretty significant. When streaming flash video XenDesktop consumed 3Mbps compared to View’s consumption of 29Mbps. The conclusion that Miercom came to was that “Citrix XenDesktop 4 enables businesses to deploy VDI in larger scale and supports Flash video far better than VMware View 4. This report to me seemed heavily scored on bandwidth consumption alone. The conclusion that I would come to is that, yes, Xen consumes far less bandwidth…period. To me this is a very one sided effort by Citrix, to make their product seem superior to VMware’s. I can’t say that you can objectively get the whole picture based off of this report. Click here to read the full report with stats and diagrams.

Next up, VMware. VMware has not participated in one of these reports. Remember now, the Miercom report was commissioned and paid for by Citrix, so you can’t consider it completely unbiased in it’s research. We only know very “birds-eye-view” details in the configuration of the VMware components, if you read the report you can clearly see the difference in detail that Citrix goes into about the configuration of their components vs. VMware’s. That being said, there was a rebuttal to the Miercom report. Here are some excerpts from a blog post by Mike Coleman which appeared on the VMware View blog back in March 2010 (one month after the report surfaced):

Recently Miercom published a report that was commissioned and paid for by Citrix. VMware did not participate in these tests they, and we have no knowledge around how Miercom/Citrix set those tests up, how they configured VMware View 4, or how they arrived at some of their conclusions. All that being said, we would gladly welcome the opportunity to take part in unbiased, apples to apples comparison with Citrix as we’re confident that VMware View can stand on its own.

In a comparison of Virtual Desktop Infrastructure (VDI) implementations, Citrix XenDesktop 4 provided better overall performance when compared to VMware View 4

It appears that the Miercom report did not consider the image quality of office applications. XenDesktop 4 uses lossy client side image caching compared to VMware View 4’s lossless techniques, which favor the View 4 user experience. Many customers insist on lossless image delivery – image compression artifacts are totally unacceptable to them. The PCoIP protocol provides network efficient progressive image refinement that builds the desktop image to a lossless image. As a result, View is consistently chosen to deliver a high-quality desktop experience.

XenDesktop 4 used 64% less bandwidth than View 4 with PCoIP for typical tasks

In our testing utilizing the Sysmark benchmark View 4 used 40% less bandwidth when run on a 1Mbps network compared to running the same test on a 100Mbs network. However, XenDesktop 4 used essentially the same bandwidth in both cases – pointing out the weakness of a fixed quality system – Citrix cannot take advantage of additional network resources when available. Miercom used 100Mbps as their ‘WAN’ for the single user test which skews the results and is not a real deployment scenario. To reiterate – the PCoIP protocol dynamically adapts the image quality based on the available network resources – thusly View 4 favors the best user experience when operating on an unconstrained network. So using a single user session to measure bandwidth performance is not a valid testing scenario. A more realistic scenario would be to compare View 4 to XenDesktop 4 on a constrained network supporting multiple users – this would result in significantly less bandwidth used by each View 4 session, while giving the best experience possible for the concurrent users.

Flash video was delivered with an average of 65% less CPU usage, 89% less bandwidth, and excellent Quality of Experience by XenDesktop 4 compared to View 4

Part of the strength of PCoIP is the fact that it adapts to the network. So, if you were to test a single desktop, as an example running multimedia, then you would observe that PCoIP consumed whatever bandwidth was available at the time. If bandwidth is available, it will use it to deliver the highest quality experience. If bandwidth is restricted, as is recommended in constrained environments, PCoIP “throttles down” to consume less bandwidth and is a “good citizen” in the network. Our customers report that PCoIP has been game changing for them and enables the delivery of a desktop environment that is secure, scalable, and easy to manage. With regards to the flash video test, this is not an apples to apples comparison – since the tests were conducted running Flash redirection with an unrealistically high packet loss of 0.5 to 5%. A correctly provisioned network will have packet loss of 0.1% or less which would result in great video performance.

Overall, XenDesktop 4 uses system resources more efficiently and is capable of scaling more effectively

Interesting that Miercom/Citrix does not call out the management costs of HDX Flash optimization/redirection. In addition to requiring a more powerful (and costly) client, the client media CODECs must be constantly updated as Adobe, Microsoft etc update their media protocols. Only VMware View 4 supports a true zero client on the desktop to provide the lowest operation cost, highest security and future-proof scalability (supports any media or graphics). In closing, we really do believe that VMware View is the only desktop virtualization product that has been designed from the ground up to deliver and manage virtualized desktop environments as a service. And, we do that with less cost and complexity than any other solution on the market.

A great argument made by VMware. No, VMware didn’t have numbers or diagrams or an outside consultant come in to validate their product, did they need to? I feel like the product speaks for itself. Again, maybe Citrix XenDesktop doesn’t work for your infrastructure, the same could apply to VMware View. In conclusion, it all comes back to making the decision that fits best with your infrastructure’s needs/wants/goals. Marketing, reports, or numbers shouldn’t sway you. Get an evaluation copy from both vendors and do a test run, this is the only true way to decide on who comes out on top, Citrix or VMware.


Greg W Stuart
Greg is the owner and editor of He's been a VMware vExpert every year since 2011. Greg enjoys spending time with his wife and 3 kids. He works as a Sr. Consultant at VMware and resides in Northern Virginia, 15 minutes west of Washington DC.

13 thoughts on “Citrix vs. VMware, who comes out on top?

  1. Greg, awesome read. VMware’s rebuttal was very interesting.

    Are you going to test View for your project, or are you stricting testing with XenDesktop?

    1. Mike,
      I already have View 4.0 in place. We have about 5 users in a test bed right now on View. We were trying to test drive a bunch of different thin clients, and it quickly became a “Let’s test everything” project. So now we are testing other VDI solutions as well. View is great in my book, I love it, it’s easy to set up and it’s reliable, good displayback too.

  2. Hey Greg,
    Very impressive post! Obviously you spent a lot of time and energy on this post. I appreciate it and I’m sure the other readers do too. Keep up the great work!

  3. a very nice article. gives a good idea on both the platforms.
    I am very interested in the virtual environments.
    Thanks for the work! 🙂

    1. Thanks for the comment Sid, I did a good bit of research and was slightly appalled at the bias that Citrix brought to their investigation. I thought it was a good rebuttal on VMware’s part. Thanks for reading.

  4. Nice post Greg. We are currently in the process of deciding on XenDesktop or VMware View. What do you think about the Citrix Intellicache announcement and do you see it as a game changer like Citrix is saying it will be?

    1. Will,
      Thanks for the reply. I really don’t see Intellicache being a game changer. If I were you I would stick with VMware View, it’s a great product, I use it in my datacenter and I love it. It’s easy to install, configure and maintain and the options for thin clients out there today are endless and most of them are great products. My favorite is NComputing’s line of “zero clients” check them out, test some thin clients before you decide on which VDI instance is better for your IT infrastructure, but personally I’ve tested both and would go with VMware View 4.5.


    2. i am doing the same test with vmware view 5 and xendesktop to deploy vdi over vpn to retrieve real monitor video for camera system so far citrix works fine so tomorrow i will deploy view .the only thing is one agent has to access multiple vdis at the same tuime which citrix does well so still evaluating the vmware

  5. Great Post !! I like both but still it depends on the business model. If you are on WAN, clearly view is not good.

    Good Work !!!

  6. PCoIP vs. ICA/HDX: A Simple Experiment a post done by Chris Wolf check the website you will see that in any scenario Citrix beat View you can see this by user experience that is slight better for a reasonable latency and also you can compare using the time recording take by Chris when use Citrix versus Vmware view that in my opinion also count because reflect the time that he have need to perform the same task over both solutions.
    Another thing that you don’t mention is the other products around Xendesktop like:
    Xenserver, vmware has Vsphere,
    Access gateway citrix have Vmware no,
    stream image to Hypervisor,Physical machines over Lan citrix have PVS Vmware can do only to their Hypervisor using Storage capababilities,
    terminal server option Citrix is leader Vmware no product (and many of the cases customer can do the same using the TS/Xenapp instead of a VDI solution and is MUCH more cheaper),
    Windows Profile Mgm Citrix have and is in PRD Vmware buy a company but not out there yet,
    recording session Citrix yes vmware no
    Client Hypervisor (Type 1) citrix yes vmware no,
    Client Hypervisor (Type 2) citrix no vmware yes
    Protocol (very Important) Citrix have ICA Vmware no protocol, have a OEM with Teradici and the list continues like Netscaler, Branch Repeater, Citrix receiver etc…in my point of view citrix is ahead because their product adapt to the most of scenario comparing with Vmware that only have View that is a OEM with Teradici they don’t control the protocol and is UDP..not easy to be accepted by many securety team 🙂 plus give more way to delivey comparing with Vmware.


  7. You raise some good points about VMware View with PCoIP vs. ICA/HDX. The fact is that PCoIP is certainly a great display protocol. However in some scenarios of high latency/low bandwidth remote connections (like over certain WANs), you may need to complement the VMware View deployment with Ericom Blaze, a software-based RDP acceleration and compression product that provides improved performance over WANs and other slow networks. Besides delivering higher frame rates and reducing screen freezes and choppiness, Blaze accelerates RDP performance by up to 10-25 times, while significantly reducing network bandwidth consumption especially over low-bandwidth/high latency connections.

    You can use VMware View with PCoIP for your LAN and fast WAN users, and at the same time use VMware View with Blaze over RDP for your slow WAN users. This combined solution can provide enhanced performance in both types of environments, letting you get the best out of VMware View for your users.

    Read more about Blaze and download a free evaluation at:


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