Simple wp-cli based benchmark command

wp-benchmark.php

<?php

if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
        return;
}

/**
 * Implements example command.
 */
class Benchmark_Command extends WP_CLI_Command {

        /**
         * Runs mail benchmark
         *
         * ## OPTIONS
         *
         * [--iterations=<integer>]
         * : How many iterations to run
         *
         * ## EXAMPLES
         *
         *     wp benchmark mail --run=10000
         *
         * @when before_wp_load
         */
        function mail( $args, $assoc_args ) {
                $assoc_args = array_merge( array( 'iterations' => 1000 ), $assoc_args );
                $iterations = (int) $assoc_args['iterations'];
                $start = microtime( true );
                for ( $i = 0; $i < $iterations; $i ++ ) {
                        wp_mail( 'admin@example.org', 'A follow up short email', 'Short email' );
                }
                $end = microtime( true );

                $duration = $end - $start;

                WP_CLI::success( "$iterations runs took $duration ms" );
                exit;
        }
}

WP_CLI::add_command( 'benchmark', 'Benchmark_Command' );