Enabling Speed Screen Latency Reduction

Citrix developed the SpeedScreen latency features to improve the user experience over high-latency connections. SpeedScreen improves the user experience by providing immediate mouse and keyboard feedback to the client, effectively making the connection appear real-time even when it is significantly delayed. Latency reduction is available only if a client is connecting to a server that is configured for latency reduction.

SpeedScreen is set and configured both at the server side and on the client side. The client side options are Auto, On, and Off. By default, the client connections are set to Auto. The server side is configured using the SpeedScreen Latency Reduction Manager utility (choose Start | Citrix | MetaFrame XP | Speed Screen Latency Reduction Manager). Figure 14-4 shows the SpeedScreen Latency utility running on the MetaFrame server.

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There are two specific actions that the SpeedScreen Latency Protection feature will take when turned on (or when high l atency is d^tesctesd):

■ Local Text Echo Local Text Echo allows the ICA client software to create font characters locally on the client device without waiting for them to be sent to the MetaFrame server and then updated on the client display. When a session begins, the ICA client sends the server a list of fonts installed on the client device. As a user types a font, the local font is displayed the instant the key is depressed, giving the user immediate feedback. This feature is very useful for users over high-latency connections who do a lot of typing, as it removes the annoyance of waiting for the typing to catch up.

■ Mouse Click Feedback When Mouse Click Feedback is enabled, the cursor on the client changes from the normal select pointer (usually an arrow, depending on the mouse pointer scheme chosen) to the working-in-background pointer (usually a pointer with an hourglass). Since mouse click feedback is performed on the ICA client, the client can provide instant click feedback to the user, even if the server hast't recognized the click yet. Anyone who has worked on a very slow PC understands how useful this feature is in reducing frustration caused from clicking multiple times on an sbject when it isn't clear whether the first click actually worked. When the server finally catches up with the number of clicks implemented, multiple instances are now open, and the user experience spirals downhill from there.

When the client is set to Auto, the default secver setticgs turn these features on when the server sees latency of 500 ms or more. We resommend changing the deCault SpeedScreen Latency Threshold settings to 150 m s for tSe high-latency threshold, and 75 ms for the low-latency threshold. These settings ensure this feature is indeed activated at times when user experience is poor.

For known, slower connections (for example, if you are connecting over a wWAN or dial-in connection), set the client mode to On to force the feature on, regardless of the latency detected by the server.

To set the client mode to On via the Web Interface Server, edit the template.ica file and add the following entries:

ZLMouseMode 1 (0-disabled, 1-enabled, 2-auto) ZLKeyboardMode 1

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