XCache is a open-source opcode cacher, which means that it accelerates the performance of PHP on servers. It optimizes performance by removing the compilation time of PHP scripts by caching the compiled state of PHP scripts into the shm (RAM) and uses the compiled version straight from the RAM. This will increase the rate of page generation time by up to 5 times as it also optimizes many other aspects of php scripts and reduce serverload.
The XCache has improved my sites performance. Look at the admin page of XCache below.
The XCache Init Time is 2012-10-28 02:41:05. Until now, 2012-10-30 14:59:00, there are 373,367 hits on cache.
I give 32MB for PHP Opcode Cache, 8 MB for Variable Cache. It looks Opcode Cache is 73% used. Variable cache has 92% available.
The main PHP program running on server are a wordpress blog, one home brewed site, and one MovableType Blog.
Some test shown that the sites are load faster than that without XCache.
I installed XCache on all VPS I have to improve the performance.