DaVinci Resolve render cache is a media optimization feature that creates temporary proxies of clips in a timeline. These files are rendered at the timeline resolution in a codec chosen for optimal real-time playback by the host system when it lacks the performance to to play the source media natively. The resolution and codec for these proxy files, as well as the render cache destination folder is set in DaVinci Resolve project settings.
Resolve manages the render cache internally. The cache files cannot be used outside of Resolve and are recreated automatically any time changes are made to the clips in the timeline.
Render cache can be set to render files based on Fusion output or Color output. The order in which operations are processed in DaVinci Resolve is first through Fusion and second through Color.
When render cache is set to Fusion output, the native source media is processed through any operations set up in Fusion and the output of Fusion only is rendered to cache. These cache files are then passed on to the Color tab.
When render cache is set to Color output, the native source media is processed through any operations set up in both Fusion and Color, and the resulting output of all operations is rendered to cache.
Render cache differs from optimized media in that only the cut sections of source clips used in the timeline are rendered, not the entire source clip.