Sure.
PHP, like most modern scripting languages (Perl, Python, etc), uses a variant on a
virtual machine, like Java and MS's .NET.
When you visit a PHP script, PHP will parse the script, turn it into bytecode, then run the bytecode on its own internal engine.
Bytecode caches intercept that process. If the script you're visiting has already been compiled, the compiled bytecode is loaded instantly, either from an in-memory or on-disk cache. Most caches will also try to optimize the compiled bytecode.
The end result is
much faster PHP speeds.
There are really only two options available nowadays:
- The Zend Optimizer, by the company that makes PHP itself:
http://www.zend.com/store/products/zend-optimizer.php- The Turck MMCache, which is so good that the guy behind it was hired by Zend:
http://turck-mmcache.sourceforge.net/There were a few more players in the market, but they seem to no longer be updated and only work with really old PHPs.
Installing and properly configuring one of these caches can result in really dramatic performance improvement...
