How can PHP developers ensure that a file is called and executed parallel to the main script without affecting performance?

PHP developers can use the `exec()` function to call and execute a file parallel to the main script without affecting performance. This function allows the main script to continue running while the called file is executed separately. By using this method, developers can achieve parallel execution without slowing down the main script.

// Call and execute a file parallel to the main script
exec('php path/to/parallel_script.php > /dev/null 2>&1 &');