The QuickView tab provides an alternate way to view your composition outside the Canvas as you work. It takes advantage of the ability of Final Cut Pro to cache frames of your sequence to RAM as you play it. This is useful for fast previews of complex composites and effects. It’s also a good way to see how your final composite looks if you are zoomed in to the Canvas while making adjustments. For example, if you zoom in to the Canvas to build a complex keyframed motion path, you can still view the composition in its entirety in the QuickView tab to see how it looks.
Tip: You can add, delete, or modify a clip’s motion and filter parameters in the Viewer and see the results update automatically in the QuickView tab, even while the clip continues to play back. Unlike other windows in Final Cut Pro, the QuickView tab loops playback until you stop it. For example, you can adjust a color correction filter while you watch a clip play back.
Note: The QuickView tab is for viewing purposes only. You cannot drag clips to this tab to perform an edit. The QuickView tab also has no effect on rendering or output from Final Cut Pro.
Choose Tools > QuickView (or press Option-8).
This section describes the controls in the QuickView tab (which appears in the Tool Bench window).

QuickView playback relies, in part, on the amount of memory allocated to Final Cut Pro. Based on this allocation, Final Cut Pro caches to RAM as much of the sequence between the In and Out points set in the Timeline as possible for accelerated playback.

If an In point is set in the Timeline but no Out point is set, Final Cut Pro caches video from the In point through the duration specified by the Range slider for playback in the QuickView tab.

If neither an In nor an Out point is set in the Timeline, Final Cut Pro uses the position of the playhead, caching half of the duration specified by the Range slider before the position of the playhead, and half after the playhead, for playback in the QuickView tab.

Video is cached to RAM as it’s played. Once the portion of the sequence that you’ve specified for QuickView playback has played all the way through, subsequent loops play much faster because they’re being played back directly from RAM.