Siarhei Siamashka, a senior software engineer at Nokia in Finland, continues to viciously focus on ARM performance improvements, particularly for the ARM NEON. There's also bug-fixes, but the ARM optimizations from Siarhei come in the form of adding various fast paths that are specific to the ARM NEON and taking available of its available CPU features.
Aside from the ongoing ARM work from Nokia, there are also performance improvements for bit-map filling in Pixman 0.21.4. There's also improvements to their test suite and also refactoring of the image access code.
The Pixman 0.21.4 release announcement can be found on xorg-announce for this library that plays a critical role to X and Cairo.
At the same time as delivering this new development snapshot, Soeren Sandmann also announced the stable release of Pixman 0.20.2. The release announcement can be found here, but it's not particularly exciting unless you're impacted by one of the bugs that this point release fixes.