In a recent post to his blog Patrick Allaert takes a look at benchmarking what Zend Platform has to offer against its open source brothers, Xdebug and APC.
The benchmark has been realized on an Intel Core2 Duo CPU T7500 @ 2.20GHz with 2Gb of RAM running Gentoo with a 2.6.25-r7 linux kernel. ab, the Apache Benchmark tool, has been used for the benchmark with 3000 requests and three concurrency modes: -c1, -c5 and -c50 which represents respectively 1, 5 and 50 simultaneous users. The application tested is eZ Publish 4.0.1 with default configuration using the "plain_site" example.
He tested with a number of different PHP installations including a base install of PHP 5.2.6, one including APC, another with APC+Xdebug and others with the Zend Platform. The resulting stats are included as well as a graph showing their relationships to each other. The installs using the bytecode caching came out on top (obviously) with the APC installations being much faster than the accelerated Zend Platform.