Article ID: 950326 - Last Review: March 27, 2008 - Revision: 1.0

You experience slow printing performance when you print to certain LPR printers on a computer that is running Windows Vista, Windows Server 2003, or Windows XP

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SYMPTOMS

Consider the following scenario:

You are using a computer that is running Windows Vista, Windows Server 2003, or Windows XP.
You try to print to a Line Printer Remote (LPR) printer by using LPR port monitor software or TCP/IP port monitor software.

In this scenario, you experience slow printing performance.

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This problem occurs because some printers use delayed acknowledgement (ACK) algorithms to decrease TCP overhead. A delayed ACK of up to 200 milliseconds may occur if a printer that uses these algorithms receives an odd number of packets from a computer that sends print jobs to the printer. During this 200-millisecond delay, the computer waits to send additional data to the printer. These 200-millisecond delays accumulate over time, and they eventually cause a significant reduction in the overall transfer speed of the print job.

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WORKAROUND

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756 (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows

To work around this problem, increase the size of the default Winsock send buffer, and then use the LPR port monitor to send the print job. To increase the size of the buffer, follow these steps.

Click Start, click Run, type regedit, and then click OK.
Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters
On the Edit menu, point to New, and then click DWORD Value.
Type DefaultSendWindow, and then press ENTER.
In the details pane, double-click DefaultSendWindow.
Click Decimal, type 64512 in the Value data box, and then click OK.
Exit Registry Editor.

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MORE INFORMATION

For more information about the DefaultSendWindow registry value, visit the following Microsoft TechNet Web site:

http://technet2.microsoft.com/WindowsServer/en/library/94d21089-411b-4bce-a823-49a77a46e7661033.mspx?mfr=true (http://technet2.microsoft.com/WindowsServer/en/library/94d21089-411b-4bce-a823-49a77a46e7661033.mspx?mfr=true)

For more information about a similar behavior in Winsock applications, click the following article number to view the article in the Microsoft Knowledge Base:

823764 (http://support.microsoft.com/kb/823764/ ) Slow performance occurs when you copy data to a TCP server by using a Windows Sockets API program

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