How can error handling, such as using the 'E_STRICT' error level, affect the speed and performance of PHP 5 scripts?

Using the 'E_STRICT' error level in PHP 5 can slow down the execution of scripts as it enforces strict standards and additional checks. To improve the speed and performance of PHP scripts, it is recommended to disable 'E_STRICT' error reporting unless necessary for debugging or compliance reasons.

// Disable E_STRICT error reporting to improve speed and performance
error_reporting(error_reporting() & ~E_STRICT);