K-Cycles is a custom build of Blender focused on optimizing the Cycles render engine for improved performance and extended feature sets. It introduces tools for real-time viewport lighting, post-processing effects, and advanced denoising capabilities without relying on the compositor.

The build includes an Ultra Lighting system with light mixing, lightgroups, and advanced light and shadow linking capabilities. Users can apply post-processing effects directly in the viewport, such as bloom, flares, anamorphic ghosts, and tone mapping. Additionally, it integrates Intel and OptiX temporal denoising technologies for still images and animations, and provides specific performance modes, global illumination presets, and memory management features like GPU Boost.