This "addon" packages Cm_Cache_Backend_Redis and Credis with a little glue-code to provide a Zend Cache for Redis. For best performance, install the php extension: phpredis
Additionally, this addon implement caching of thread counts in a forum.
As for clustering, the Zend component doesn't yet support it. There is some ongoing open source development to extend it. But it has been stalled for about 6 months.
Optionally, pipelining can be enabled in XenForo_Model_DataRegistry::getMulti by adding the following lines to config.php. Preferably after setting up the cache.