Generally, Temporary Buffer files are recommended if your processor cannot process information as quickly as your CD-ROM drive can read it. Because VBR encoding varies the load on your processor from frame to frame, Xing recommends always using a Temporary Buffer file whenever encoding files using the VBR option.
A Temporary Buffer is actually a temporary file (sometimes known as a swap file), that is written to your hard disk during the ripping and encoding process. When you finish encoding the file, the Temporary Buffer file is erased.
The purpose of a Temporary Buffer is to store temporary information in a location where the Encoder looks to find it, and requests it as needed. This location on your hard disk is called the Scratch Disk. The Temporary Buffer file requires a substantial amount of disk space on your Scratch Disk - about 10MB per minute of music.
Apple recommends that you always use a Temporary Buffer.
To use a Temporary Buffer file: