Panel: Properties editors ‣ Backdrop

Backdrop Options.

Backdrop Channels
Set the image to be displayed with Color, Color and Alpha, or just Alpha.
Sets how big the backdrop image is.
Change the screen space position of the backdrop, or click the Move button, or shortcut Alt-MMB to manually move it.
Automatically scales the backdrop to fit the size of the Node editor.



Panel: Properties editors ‣ Performance

Performance Settings.

This panel help you to tweak the performance of the compositor.

Sets the quality when doing the final render.
Sets the quality when making edits.
Chunk Size
Max size of a title (smaller values give a better distribution of multiple threads, but more overhead).
This allows the use of an OpenCL platform to aid in rendering. Generally, this should be enabled unless your hardware does not have good OpenCL support.
Buffer Groups
Enables buffering of group nodes to increase the speed at the cost of more memory.
Two Pass
Use two pass execution during editing: first calculate fast nodes, the second pass calculate all nodes.
Viewer Border
This allows to set an area of interest for the backdrop and preview. The border is started by Ctrl-B and finished by selection of a rectangular area. Ctrl-Alt-B discards the border back to a full preview. This is only a preview option, final compositing during a render ignores this border.
Highlights the nodes that are being calculated by the compositor.