Citrix ICA Latency: Solving Network Slowdown

ExtraHop helped a research hospital remove barriers to expansion for its VDI deployment, which supports 4,000 users and more than 100 applications.


Virtual desktop infrastructure (VDI) is a big deal for healthcare providers, government agencies, professional services firms, and other organizations with distributed, mobile workforces. As these VDI deployments scale out, they typically run into performance issues caused by resource contention and other pressures on the support infrastructure.

Nurses and doctors logging into their virtual desktops reported extremely slow login times at around 8:30 a.m. every morning. The IT Operations team at the hospital had tried to solve this problem for months without success. The CIO described the problem as a "ghost in the machine."


Troubleshooting VDI performance problems in large enterprise environments is not for the faint-hearted. Traditional Citrix monitoring tools use agents installed on the Citrix servers to scrape event logs, providing some forensic analysis capabilities at the cost of onerous CPU overhead.

However, Citrix administrators also need visibility across other tiers of the application delivery chain to pinpoint the root cause of performance problems. They need to be able to answer questions such as:

  • Is the Active Directory server slow?
  • Are there network issues in the Citrix cluster?
  • Is there contention in the SAN?

Because the IT Operations team at the research hospital relied on discrete monitoring tools that covered siloes of the Citrix environment, they could not discover what caused the slow logins.


After the research hospital deployed ExtraHop, they monitored the slow logins and found one user had stored 2GB of photos in the My Pictures folder. As this user logged in each morning, his profile would pull down 2GB of photos from storage and consequently slow everyone else's logins. Once the issue was identified, the IT team removed the My Pictures folder from everyone's profile and fixed the problem.

On the front end, ExtraHop uses industry-leading ICA transaction analysis to provide deep visibility into the end-user experience, showing things like Citrix ICA session latency, slow logins, application load time, application latency, applications individual users are running, and the virtual channels being used by those applications.

However, in this case, rapid diagnosis was possible because ExtraHop also analyzes the entire supporting infrastructure, including the network, directory services, application servers, databases, and storage.


This research hospital plans to continue expanding its VDI deployment to its research arm. Having witnessed how ExtraHop helped to rapidly troubleshoot the slow login issue, the hospital's CIO is confident about the planned expansion and plans to use ExtraHop to further improve login and application load times.

VDI deployments should increase efficiency and flexibility. When working properly, they ease desktop maintenance, facilitate BYOD, support expansion, and help secure your network. What does it cost you when something breaks—when client latency is not just noticeable, but unbearable? Lost productivity and days of troubleshooting and triaging can add up to tens of thousands of dollars very quickly. ExtraHop helps to ensure VDI deployments are successful by showing how front-end user experience is tied to activity on the backend infrastructure.

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