Q: What XenApp polices can help improve session performance for users ?

A: XenApp has many policies for different situations that can help a Citrix Administrator tweak session performance especially if users are running multiple monitors , streaming video\multimedia, or over low bandwidth connections.

The following policies can be found in the Citrix Delivery Services Console (XA 6.0) or The Citrix AppCenter Console (XA 6.5) under the policies node section of the console:

XenApp Computer Policies:

ICA > Graphics > Display memory limit

• Test doubling the default value of 32768 to 65536, this is especially needed and helpful for users with multiple monitors.

ICA > Graphics > Queuing and tossing

• Set to Enabled if using graphic intensive applications that have a large amount of redundant images as this can cache those images on the client and improve the performance of those applications.
• Set to Disable if you are not using any graphic intensive applications to skip the caching process which may improve the responsiveness of the applications.

ICA > Graphics > Dynamic Windows Preview

• Set to Disabled to disable dynamic windows previews for seamless applications (Flip, Flip 3d, Taskbar  Preview, and Peek). Which will Instead present users with small application icons.

ICA > Multimedia > Windows Media redirection

• Set to Allowed to provide a better quality and experience for users as it allows multimedia files to be played on the client machine instead of the server.
• Set to Prohibited if the users devices are not as powerful as the server or running over low bandwidth connections.

ICA > Multimedia > Windows Media Redirection Buffer Size Use

• Set to Enabled if the system automatic buffering is not providing the best user experience or performance for example if users are constantly complaining about video choppiness they may not be getting enough of the video buffered in this case you would enable this policy and the Windows Media Redirection Buffer Size policy.

ICA > Multimedia > Windows Media Redirection Buffer Size

• This is only used when Windows Media Redirection Buffer Size Use is enabled start with the highest setting of 10 seconds and lower it until you find an acceptable buffer size for your users.

XenApp User Policies

ICA > Adobe Flash Delivery > Flash Redirection

• Set to Enabled to allow flash content to be rendered on the client usually resulting in a better experience for the client.
• Set to Disabled if the client are unable to render flash on their machines or the session performance is degrading when running flash content this will allow the XenApp server to render the flash content for the user. 

ICA > Adobe Flash Delivery > Flash Intelligent Fallback

• Set to Enabled so XenApp will calculate which will provide the best performance for users when rendering flash content it will decide where it is rendered the client or the XenApp server.

ICA > Audio > Audio Quality

• Set to Low - If users have limited bandwidth to improve session performance over audio quality
• Set to Medium - if you want a little better audio quality but willing to sacrifice some session performance (This is the minimum requirement for speech voice over ip applications)
• Set to High - If bandwidth is not an issue for the best audio quality.

ICA > Bandwidth

• There are various policies for bandwidth control over users ICA sessions if you need to restrict certain ICA virtual channels from using all the available bandwidth a user has which in turn could create performance issues with the session for example if you had an application with High Definition Audio that plays long speeches it may use most of the available bandwidth from the users session resulting in poor session performance. This section allows you to limit what each ICA virtual channel is allowed to use *Recommended for experienced XenApp administrator only*

ICA > Desktop UI > Desktop Wallpaper

• Set this to Prohibited to improve session performance (this takes away desktop wallpaper in users sessions)

ICA > Desktop UI > Menu Animation

• Set this to Prohibited to improve session performance (this takes away the Microsoft menu animations)

ICA > Desktop UI > View window contents while dragging

• Set this to Prohibited to improve session performance (If a user drags an application window it will show the outline of the application instead of its contents)

Visual Display > Max Frames Per Second

• Set it to 30 , to improve the responsiveness of graphic extensive applications and the users experience when bandwidth is not a concern.
• Set it to 15 or 10 - If bandwidth and overall session performance are a concern and you are not using any graphic intensive applications that need to show immediate updates.

Visual Display > Moving Images > Progressive Compression Level

• Set it to Ultra High - Provides the best session performance with the least amount of image detail ideal for low bandwidth connections.
• Set it to Medium - Provides the middle ground of good image detail with good session performance.
• Set it to None - Provides the best image detail but uses the most bandwidth.

Visual Display > Still Images > Extra Color Compression

• Set this to Enabled to improve responsiveness over image quality for users.(Only for XenApp 6.5 and above)

Visual Display > Still Images > Heavyweight Compression

• Set this to Enabled to reduce bandwidth without losing image quality at the expense of the XenApps Servers CPU power.

Visual Display > Still Images > Lossy Compression Level

• Set this to High for the best session performance on when using graphic intensive applications with a slight loss in image detail (if you are using medical applications and viewing X-RAYs for example where every detail is needed you may need to set this to None so there is no loss in image detail but it will take up more bandwidth)

Note: These are the most common polices used to tweak XenApp session performance , it is recommend to test all policy settings on a test XenApp server using a test user account before implementing any of these policy settings into a production environment.

Citrix Documentation - XenApp Policy Settings: Quick Reference Table

This article goes over the various XenApp polices that can be used to tweak minor user session performance issues in XenApp.