WordPress: Times how long it takes each filter and action to run and displays results at the end of the page. Quick and dirty.

Wordpress slow hooks timer

<?php

//add this in your theme's functions.php to time all the hooks

// Here's a test to make sure it's working
//add_action( 'wp_footer', function() { sleep( 2 ); } );


class WhatIsSoSlow {

	public $data = array();

	function __construct() {
		add_action( 'all', array( $this, 'filter_start' ) );
		add_action( 'shutdown', array( $this, 'results' ) );
	}

	// This runs first for all actions and filters.
	// It starts a timer for this hook.
	public function filter_start() {
		$current_filter = current_filter();
		
		$this->data[ $current_filter ][]['start'] = microtime( true );

		add_filter( $current_filter, array( $this, 'filter_end' ), 99999 );
	}

	// This runs last (hopefully) for each hook and records the end time.
	// This has problems if a hook fires inside of itself since it assumes
	// the last entry in the data key for this hook is the matching pair.
	public function filter_end( $filter_data=null ) {
		$current_filter = current_filter();
		
		remove_filter( $current_filter, array( $this, 'filter_end' ), 99999 );

		end( $this->data[ $current_filter ] );

		$last_key = key( $this->data[ $current_filter ] );

		$this->data[ $current_filter ][ $last_key ]['stop'] = microtime( true );

		return $filter_data;
	}

	// Processes the results and var_dump()'s them. TODO: Debug bar panel?
	public function results() {
		$results = array();

		foreach ( $this->data as $filter => $calls ) {
			foreach ( $calls as $call ) {
				// Skip filters with no end point (i.e. the hook this function is hooked into)
				if ( ! isset( $call['stop'] ) )
					continue;

				if ( ! isset( $results[ $filter ] ) )
					$results[ $filter ] = 0;

				$results[ $filter ] = $results[ $filter ] + ( $call['stop'] - $call['start'] );
			}
		}

		asort( $results, SORT_NUMERIC );

		$results = array_reverse( $results );

		echo '</div></div></div></div><pre style="z-index: 9999;position: relative;background-color: #0ff6;margin-left: 200px;">'.print_r( $results, true ).'</pre>';
	}
}

new WhatIsSoSlow();