Auto clear Autoptimize cache before it gets too large

Autoptimize “makes optimizing your site really easy. It can aggregate, minify and cache scripts and styles, injects CSS in the page head by default (but can also defer), moves and defers scripts to the footer and minifies HTML”, thank you to the plugin authors they have done a great job in making this plugin available and free for everyone. The plugin is almost perfect but doesn’t offer a proper schedule purging mechanism. On this post you will find two different approaches to tackle this “issue”.

The code snippet below added to your theme functions .php will limit the Autoptimize cache to 256MB. Thank you to @rahulpragma to make the below snippet available


# Automatically clear autoptimizeCache if it goes beyond 256MB
if ( class_exists( 'autoptimizeCache' ) ) {
    $myMaxSize = 256000; # You may change this value to lower like 100000 for 100MB if you have limited server space
    $cacheSize=round( $statArr[1]/1024 );
    if ( $cacheSize>$myMaxSize ) {
       header( "Refresh:0" ); # Refresh the page so that autoptimize can create new cache files and it does breaks the page after clearall.

The code snippet below added to your theme functions .php will schedule Cron job to delete the cache every week and month. This code snippet is a bit different from the above this code only cleans up the cache, it doesn’t limit the size of it.

namespace wppress;
class GarbageCollection {
    public function __construct() {
        add_filter( 'cron_schedules', function ( $schedules ) {
            $schedules['weekly'] = array(
                'interval' => 604800,
                'display'  => __( 'Once a Week' ),
            $schedules['monthly'] = array(
                'interval' => 2635200,
                'display'  => __( 'Once a month' ),
            return $schedules;
        if ( ! wp_next_scheduled( 'wppress/garbage/clear') ) {
            wp_schedule_event(time(), 'monthly', 'wppress/garbage/clear' );
        add_action( 'wppress/garbage/clear', [ &$this, 'clear'] );
    public function clear()
        if ( class_exists( '\autoptimizeCache' ) ) {
            /* Clear autoptimize cache once a month */
new GarbageCollection();



I am a Freelance Web Developer and WordPress Expert based in London with a wealth of website development and support experience. I am great at problem solving and developing quick solutions.

20 thoughts on “Auto clear Autoptimize cache before it gets too large

  1. This is great, thank you – exactly what I needed. Nowhere in the Autoptimize documentation was there anything about autoptimizeCache::clearall(); function… I was under the impression there was no way to trigger the cache clear other than through wp-admin or via some janky workaround that are smattered all over the net. Appreciate it!

  2. Hi Nuno,
    first of all thanks for the snippets.

    However I’m a little bit confused about the second one: you say to put it in functions.php but the tags “” at the end suggest it should be copied into a stand-alone php file.

    What’s the right thing to do?

  3. Hi Nuno,

    Thank you for this post. I appiciate your effort. I use first solutio but after x amount of mb when cache need to be cleared, webiste keep autorefreh without deleting cache, and it’s stuck in the loop and refreshes website. Any idea why this is so? Thank you for your time.

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