1) Can you recommend me a PHP accelerator for PHP V5.2.6?
2) Do you know about any recent test comparation/review of those modules(Alternative PHP Cache, eAccelerator, XCache, Zend Optimizer, Zend Platform, ionCube PHP Accelerator, Turck MMCache, Nusphere PhpExpress)?
APC — standard choice, included in PECL, comes prepackaged in most Linux distros, to be bundled in by default in PHP6. As a bonus it can serve as data cache (something like local memcache).
eAccelerator was popular, for some time it was the fastest bytecode cache. But the difference in speed is not enough to justify choosing it over APC.
Turck MMcache — dead. eAccelerator was forked from it.
ionCube — dead.