When using PHP versions before PHP-5.2.x, optimizing code to improve the execution speed of PHP applications is theoretically 40%-100% faster than not using ZO. The principle of implementation is to optimize the code generated by the run-time compiler (Run-Time Compiler) before being finally executed. (From Encyclopedia) And before PHP-5.2.x, PHP code encrypted and obfuscated by Zend Guard could only be run through the official Zend Optimizer.
PHP versions after PHP-5.3.x are used to strengthen the protection of PHP commercial code and improve the execution performance of PHP. Its predecessor is Zend Optimizer.
Precompiled PHP scripts can be stored in shared memory to improve PHP execution performance, so that PHP scripts do not need to be loaded and parsed on every request. After PHP-5.5, it has been bundled and released with PHP.
eAccelerator is a free and open source PHP acceleration, optimization, compilation and dynamic caching project. It can improve the performance of PHP scripts by caching the compiled results of PHP code. eAccelerator caches the compiled PHP code into shared memory. And it is directly called when the user visits to achieve efficient acceleration. Although it is a good project, it has not been updated for several years. The latest version supports php-5.4, which is of course official.
Directly compiling PHP code into opcode code is actually a mechanism for encrypting PHP code, because the opcode code only needs to be further simply serialized or obfuscated, and then decoded into opcode code after the Zend virtual machine is executed. . But the purpose of encryption is to avoid the possibility of source code analysis; and opcode is to improve the running speed of the program.
Summary: If you want to choose OPcode, just use OPcache, which is officially recommended by PHP. If your code is commercial PHP code, choose Zend Optimizer before PHP-5.2.x, but for PHP-5.3+ version, you need to use Zend Guard Loader . It is worth noting that after PHP is encrypted and optimized, you can also choose an Opcode cache.