Slow performance in applications that use the DirectWrite API on a computer that is running Windows 7 or Windows Server 2008 R2

Known Issue

Important After you install KB2505438, applications that render text by using DirectWrite may encounter errors, including application crashes. This is because the hotfix package does not contain an updated version of another driver. The hotfix package that is described in KB2454826 contains the updated version of this driver.

To resolve this issue, install Windows 7 Service Pack 1 (SP1) or KB2454826 on the computer. For more information about how to install KB2454826, click the following article number to view the article in the Microsoft Knowledge Base:For more information about Windows 7 SP1, visit the following Microsoft website:

Update information

How to obtain this update

The following files are available for download from the Microsoft Download Center:For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to obtain Microsoft support files from online services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

Prerequisites

To apply this update, you must be running one of the following operating systems:

• Windows 7
• Windows 7 Service Pack 1 (SP1)
• Windows Server 2008 R2
• Windows Server 2008 R2 Service Pack 1 (SP1)

For more information about how to obtain a Windows 7 or a Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To use the update in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this update.

Update replacement information

This update does not replace a previously released update.

File information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

The FontCache service manages a system cache and a per-user cache for each user on the computer. When the computer restarts, the DirectWrite API waits for two seconds while the FontCache service loads the system cache. Typically, the system cache has a size of 400 to 600 kilobytes (KB). When a client process loads the DirectWrite API for the first time, the DirectWrite API waits for a half second while the FontCache service loads a per-user cache.

If a client application that applies the DirectWrite API (for example, Internet Explorer 9) starts immediately after the computer starts, either of the timeouts may expire because Windows is performing many other competing I/O operations. For example, the FontCache service takes 30 seconds to load the per-user cache when Internet Explorer 9 starts. In this situation, the DirectWrite API reads the fonts directly, without access to the shared font cache. This slows down the initial start process of Internet Explorer 9. Additionally, the working set for Internet Explorer 9 is highly increased because the DirectWrite API caches the fonts in the memory space of the Iexplorer.exe processes.

Additional file information