This backwards compatible release contains a number of feature and stability improvements.
- On the HHVM front a nasty regression with APCIterator was resolved, continuing the commitment to HHVM compatibility.
- The Filesystem driver was given an alternative format, JSON, for systems where the native PHP was not optimal. This driver also saw signicant performance improvements related to the clearing functions.
- The Redis driver was given additional tests, improved error handling, and better support for persistent connections.
- Memcached also received improvements around it's use of persistent connections, as well as support for the AWS autodiscovery feature.
In addition to those points there were a few minor bug fixes as well as some readability related code improvements.