IMPORTANT FOR VISTA USERS (The read speed of the DVD-R/RW drive is much slower than the expected speed )

SYMPTOMS
On a Windows Vista-based computer, you finish recording an optical disc, such as a CD-R, a CD-RW, a DVD-R, or a DVD-RW disc. To record the optical disc, you use the DVD-R/RW drive, and you select the mastered disc format. Then, you notice that the read speed of the drive is much slower than the expected speed. This slow read speed causes the Windows Vista operating system to take more time to copy files from the drive.

Note If you use a built-in DVD drive, you must restart the operating system, or you must resume from hibernation, to reset to the default speed of the DVD drive. If you use an external DVD drive, you only have to restart the external DVD drive.
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CAUSE
When the system is writing the disc, the drive uses a slow speed. However, some drives do not automatically set the drive speed back to the default speed after the system finishes writing the disc, and the system ejects the disc. Therefore, poor performance occurs when the system reads the disc again.

http://support.microsoft.com/kb/942869

you can get the hotfix here

http://thehotfixshare.net/board/index.php?automodule=downloads&showfile=3775