Blender Introducing GPU-Accelerated, Real-Time Compositor
The Blender real-time compositor is a new GPU-accelerated compositor designed for real-time interaction. Omar Emara with Blender explained, "As a first step, this new back-end will be used to power the Viewport Compositor, a new shading option that applies the result of the Compositor Editor node-tree directly in the 3D Viewport. Artists will not have to wait for a full render to start compositing, allowing for faster and more interactive iterations on one’s projects. In the long term, the goal is for it to power the existing Compositor Editor."
The real-time compositor is still being developed and can be enabled from the preferences when using an experimental branch of Blender. While still experimental, it's considered usable currently and is expected to land in Blender's master branch while continuing to be refined.
The open-source, cross-platform Blender software continues advancing with even more features and functionality.
More details on the Blender real-time compositor via the Blender.org blog. The current status of this compositor can be tracked via developer.blender.org.