Reducing application launch time

Use the session pre-launch feature to reduce application launch time during normal or high traffic periods, thus providing users with a better experience. The pre-launch feature allows a pre-launch session to be created when a user logs on to Citrix Receiver for Windows, or at a scheduled time if the user is already logged on.

This pre-launch session reduces the launch time of the first application. When a user adds a new account connection to Citrix Receiver for Windows, session pre-launch does not take effect until the next session. The default application ctxprelaunch.exe is running in the session, but it is not visible to you.

Session pre-launch is supported for StoreFront deployments as of the StoreFront 2.0 release. For Web Interface deployments, be sure to use the Web Interface Save Password option to avoid logon prompts. Session pre-launch is not supported for XenDesktop 7 deployments.

Session pre-launch is disabled by default. To enable session pre-launch, specify the ENABLEPRELAUNCH=true parameter on the Receiver command line or set the EnablePreLaunch registry key to true. The default setting, null, means that pre-launch is disabled.

Note: If the client machine has been configured to support Domain Passthrough (SSON) authentication, then prelaunch is automatically enabled. If you want to use Domain Passthrough (SSON) without prelaunch, then set the EnablePreLaunch registry key value to false.

Caution: Editing the registry incorrectly can cause serious problems that may require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

The registry locations are:

HKEY_LOCAL_MACHINE\Software\[Wow6432Node\]Citrix\Dazzle

HKEY_CURRENT_USER\Software\Citrix\Dazzle

There are two types of pre-launch:

  • Just-in-time pre-launch. Pre-Launch starts immediately after the user’s credentials are authenticated whether or not it is a high-traffic period. Typically used for normal traffic periods. A user can trigger just-in-time pre-launch by restarting Citrix Receiver for Windows.
  • Scheduled pre-launch. Pre-launch starts at a scheduled time. Scheduled pre-launch starts only when the user device is already running and authenticated. If those two conditions are not met when the scheduled pre-launch time arrives, a session does not launch. To spread network and server load, the session launches within a window of when it is scheduled. For example, if the scheduled pre-launch is scheduled for 1:45 p.m., the session actually launches between 1:15 p.m. and 1:45 p.m. Typically used for high-traffic periods.

Configuring pre-launch on a XenApp server consists of creating, modifying, or deleting pre-launch applications, as well as updating user policy settings that control the pre-launch application. See “To pre-launch applications to user devices” in the XenApp documentation for information about configuring session pre-launch on the XenApp server.

Customizing the pre-launch feature using the receiver.admx file is not supported. However, you can change the pre-launch configuration by modifying registry values during or after Citrix Receiver for Windows installation. There are three HKLM values and two HKCU values:

  • The HKLM values are written during client installation.
  • The HKCU values enable you to provide different users on the same machine with different settings. Users can change the HKCU values without administrative permission. You can provide your users with scripts to accomplish this.

HKEY_LOCAL_MACHINE registry values

For Windows 7 and 8, 64-bit: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\ICA Client\Prelaunch

For all other supported 32-bit Windows operating systems: HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Prelaunch

Name: UserOverride

Values:

0 - Use the HKEY_LOCAL_MACHINE values even if HKEY_CURRENT_USER values are also present.

1 - Use HKEY_CURRENT_USER values if they exist; otherwise, use the HKEY_LOCAL_MACHINE values.

Name: State

Values:

0 - Disable pre-launch.

1 - Enable just-in-time pre-launch. (Pre-Launch starts after the user’s credentials are authenticated.)

2 - Enable scheduled pre-launch. (Pre-launch starts at the time configured for Schedule.)

Name: Schedule

Value:

The time (24 hour format) and days of week for scheduled pre-launch entered in the following format:

HH:MM M:T:W:TH:F:S:SU where HH and MM are hours and minutes. M:T:W:TH:F:S:SU are the days of the week. For example, to enable scheduled pre-launch on Monday, Wednesday, and Friday at 1:45 p.m., set Schedule as Schedule=13:45 1:0:1:0:1:0:0 . The session actually launches between 1:15 p.m. and 1:45 p.m.

HKEY_CURRENT_USER registry values

HKEY_CURRENT_USER\SOFTWARE\Citrix\ICA Client\Prelaunch

The State and Schedule keys have the same values as for HKEY_LOCAL_MACHINE.

Reducing application launch time