iPrint slow when workstation logs onto Windows Domain

iPrint operations, such as printing and listing printers, are slow when the Windows workstation is logged onto a Microsoft Domain.

In extreme cases, the Domain Controller's performance is affected (slowness or even crashing) when iPrint printers are installed to workstations that are part of the Domain.

Install the 4.28 iPrint client or later.

The iPrint client must validate the Windows user when checking status on a printer. The Windows Print Spooler will check printer status when:
- Printing
- Launching Applications
- Listing Printers (clicking File -> Print within an application)
- Leaving the Windows Printers and Faxes window open

When the user is local, validating the user is as quick as checking the local Windows registry. However, when the user is logged onto a Domain, the user validation requires a query sent to the Primary Domain Controller (PDC). This can be taxing if a) the PDC is far away, or b) the number of requests hitting the PDC affects the Domain Controller's performance. With the 4.26 iPrint client and earlier, the iPrint client queries only the PDC, not Backup Domain Controllers (BDC).

The 4.28 version of the iPrint client improves the problem in two ways:
a. Any Domain Controller can validate the user verification (not just the PDC).
b. The Windows user information is cached for 4 hours. This prevents the iPrint client from taxing the Domain.