Quantum is the umbrella, if you will, under which a bunch of performance focused subprojects are being developed. Some of them (Quantum Render, Quantum CSS) are

Quantum is the umbrella, if you will, under which a bunch of performance focused subprojects are being developed. Some of them (Quantum Render, Quantum CSS) are importing Servo components (WebRender and Stylo, respectively), while others (Quantum DOM, Quantum Compositor, Quantum Flow) are serious surgery on existing Gecko components.