Cairo 1.12.0 introduces a new procedural pattern (mesh gradient), a new X back-end for Cairo that's using XCB (cairo-xcb), and many performance improvements without sacrificing its composition model.
For bringing the Cairo performance improvements, the library's rasterization pipeline was overhauled and now allows for the different Cairo back-ends the ability to implement their own specific pipeline while being able to leverage a library of common routines. Clipping was also overhauled, stroking was made faster, and there's also four new anti-aliasing hints.
In terms of back-end work, the Cairo 1.12 OpenGL back-end received significant changes as it was ported to OpenGL ES 2.0 and other changes so that it could begin to exploit "advanced hardware features."
Find out more about Cairo 1.12 from the CairoGraphics.org announcement.