Citrix XenApp Performance Essentials, by Luca Dentella, is a practical guide that helps system administrators to identify bottlenecks, solve performance problems and optimize XenApp farms thanks to best-practices and real-world examples.
A well-designed infrastructure may help to solve a lot of headaches when the infrastructure is in production... in chapter 1 the book explains the most important elements of a XenApp infrastructure (session-host servers, datastore servers, web interface servers...), their role, how they work together and how to correctly size them based on the number of users and applications that will be served. This chapter includes not only best practices from Citrix, but also precious suggestions that come from author's experience with real Citrix farm.
When a farm is in production and users start to connect and work with published applications, it's very important to monitor its performance: in chapter 2 Luca explains how to monitor it, from the basic Windows Performance counters to the use of advanced Citrix tools. XenApp offers several advanced settings (CPU Utilization Management, Memory Optimization, Load evaluators
A typical complaint about applications published by XenApp is that they start slowly... this is usually because of slow session start-up. Chapter 3 teaches the most frequent causes of slowness and how to reduce the start-up time, including the use of the new features of XenApp 6.5 (Session Sharing and Lingering).
Multimedia applications are becoming more and more frequently published by XenApp farm, that's why Luca wrote a chapter, the forth, to explain the technologies Citrix offers under the brand of HDX and how you can take advantage of them for publishing video/audio/VoIP applications.
The last chapter is about remote users, i.e. users that connect to the farm using WAN (wide-area network) connections. Citrix offers different optimizations and Citrix administrators can work together with network admins to improve the user-experience with the use of QoS, priorities... It's usually hard to understand how published applications work with slow, laggy links; Luca found an opensource tool, named WanEM, that can simulate every kind of links; in chapter 5 you'll also learn how to use it.