When you render previews, Adobe Premiere Pro creates files on your hard disk. These preview files contain the results of any effects that Adobe Premiere Pro processed during a preview. If you preview the same work area more than once without making any changes, Adobe Premiere Pro instantly plays back the preview files instead of processing the sequence again. Similarly, preview files can save time when you export the final video program by using the processed effects already stored. Adobe Premiere Pro stores the preview files in a folder you can specify.

To further save time, Adobe Premiere Pro maintains existing preview files whenever possible. Preview files move along with their associated segment of a sequence as you edit your project. When a segment of a sequence is changed, Adobe Premiere Pro automatically trims the corresponding preview file, saving the remaining unchanged segment.

When completely done with a project, delete preview files to save disk space.