Pantheon Advanced Page Cache vs DietPress

For sites wanting fine-grained control over how their responses are represented in their edge cache, Pantheon Advanced Page Cache is the golden ticket. Here’s a high-level overview of how the plugin works: When a response is generated, the plugin uses surrogate keys based on WordPress’ main WP_Query object to “tag” the response with identifers for the data used in the response. See the “Adding Custom Keys” section for including your own surrogate keys. When WordPress data is modified, the plugin triggers a purge request for the data’s corresponding surrogate keys. Because of its surrogate key technology, Pantheon Advanced Page Cache empowers WordPress sites with a significantly more accurate cache purge mechanism, and generally higher cache hit rate. It even works with the WordPress REST API. Go forth and make awesome! And, once you’ve built something great, send us feature requests (or bug reports). How It Works Pantheon Advanced Page Cache makes heavy use of surrogate keys, which enable responses to be “tagged” with identifiers that can then later be used in purge requests. For instance, a home page response might include the Surrogate-Key header with these keys: Surrogate-Key: front home post-43 user-4 post-41 post-9 post-7 post-1 user-1 Similarly, a GET requests to /wp-json/wp/v2/posts might include the Surrogate-Key header with these keys: Surrogate-Key: rest-post-collection rest-post-43 rest-post-43 rest-post-9 rest-post-7 rest-post-1 Because cached responses include metadata describing the data therein, surrogate keys enable more flexible purging behavior like: When a post is updated, clear the cache for the post’s URL, the homepage, any index view the post appears on, and any REST API endpoints the post is present in. When an author changes their name, clear the cache for the author’s archive and any post they’ve authored. There is a limit to the number of surrogate keys in a response, so we’ve optimized them based on a user’s expectation of a normal WordPress site. See the “Emitted Keys” section for full details on which keys are included, and the “Adding Custom Keys” section following for information on how to add your own. Adding Custom Keys By default, Pantheon Advanced Page Cache generates surrogate keys based on an interpretation of the main WP_Query query object. Because WordPress sends headers before the page is rendered, you need to use the pantheon_wp_main_query_surrogate_keys filter to include additional surrogate keys for any data present on the page. For example, to include surrogate keys for a sidebar rendered on the homepage, you can filter the keys using the is_home() template tag: /** * Add surrogate key for the featured content sidebar rendered on the homepage. */ add_filter( 'pantheon_wp_main_query_surrogate_keys', function( $keys ){ if ( is_home() ) { $keys[] = 'sidebar-home-featured'; } return $keys; }); Then, when sidebars are updated, you can use the pantheon_wp_clear_edge_keys() helper function to emit a purge event specific to the surrogate key: /** * Trigger a purge event for the featured content sidebar when widgets are updated. */ add_action( 'update_option_sidebars_widgets', function() { pantheon_wp_clear_edge_keys( array( 'sidebar-home-featured' ) ); }); Similarly, to include surrogate keys for posts queried on the homepage, you can pre-fetch the posts before the page is rendered: /** * An example of pre-fetching a WP_Query to tag the * response with queried data. You'd use `papcx_wp_query()` * a second time within your template to use the data. */ add_filter( 'pantheon_wp_main_query_surrogate_keys', function( $keys ) { if ( is_home() ) { $query = papcx_wp_query( array( 'post_type' => 'page', ) ); foreach( $query->posts as $post ) { $keys[] = 'post-' . $post->ID; } } return $keys; }); /** * Register a 'papc-non-persistent' cache group to cache data * in a non-persistent manner. We only want data in this group * to be cached within the page request. */ add_action( 'init', function(){ wp_cache_add_non_persistent_groups( array( 'papc-non-persistent' ) ); }); /** * Helper function to instantiate a WP_Query object only * once per page request. * * @param array $args Arguments to pass to WP_Query. * @return WP_Query */ function papcx_wp_query( $args = array() ) { $cache_key = md5( serialize( $args ) ); // WP_Query object will be in cache the second time we use the function. $cache_value = wp_cache_get( $cache_key, 'papc-non-persistent' ); if ( false !== $cache_value ) { return $cache_value; } $query = new WP_Query( $args ); wp_cache_set( $cache_key, $query, 'papc-non-persistent' ); return $query; } Because Pantheon Advanced Page Cache already handles WordPress post purge events, there’s no additional call to pantheon_wp_clear_edge_keys(). Lastly, the pantheon_wp_rest_api_surrogate_keys filter lets you filter surrogate keys present in a REST API response. Additional purging by path When a post is published for the first time, the permalink’s path is also purged even if it has no matching keys. This can be further filtered with the pantheon_clear_post_path filter. add_action('pantheon_clear_post_path', function($paths) { // Add or remove paths from $paths return $paths }, 10, 3); Need a bit more power? In addition to pantheon_wp_clear_edge_keys(), there are two additional helper functions you can use: pantheon_wp_clear_edge_paths( $paths = array() ) – Purge cache for one or more paths. pantheon_wp_clear_edge_all() – Warning! With great power comes great responsibility. Purge the entire cache, but do so wisely. Ignoring Specific Post Types By default, Pantheon Advanced Page Cache is pretty aggressive in how it clears its surrogate keys. Specifically, any time wp_insert_post is called (which can include any time a post of any type is added or updated, even private post types), it will purge a variety of keys including home, front, 404 and feed. To bypass or override this behavior, since 1.5.0 we have a filter allowing an array of post types to ignore to be passed before those caches are purged. By default, the revision post type is ignored, but others can be added: /** * Add a custom post type to the ignored post types. * * @param array $ignored_post_types The array of ignored post types. * @return array */ function filter_ignored_posts( $ignored_post_types ) { $ignored_post_types[] = 'my-post-type'; // Ignore my-post-type from cache purges. return $ignored_post_types; } add_filter( 'pantheon_purge_post_type_ignored', 'filter_ignored_posts' ); This will prevent the cache from being purged if the given post type is updated. Setting the Cache Max Age with a filter The cache max age setting is controlled by the Pantheon Page Cache admin page. As of 2.0.0, there are three cache age options by default — 1 week, 1 month, 1 year. Pantheon Advanced Page Cache automatically purges the cache of updated and related posts and pages, but you might want to override the cache max age value and set it programmatically. In this case, you can use the pantheon_cache_default_max_age filter added in Pantheon MU plugin 1.4.0+. For example: add_filter( 'pantheon_cache_default_max_age', function() { return 10 * DAY_IN_SECONDS; } ); When the cache max age is filtered in this way, the admin option is disabled and a notice is displayed. Updating the cache max age based on nonces Nonces created on the front-end, often used to secure forms and other data, have a lifetime, and if the cache max age is longer than the nonce lifetime, the nonce may expire before the cache does. To avoid this, you can use the pantheon_cache_nonce_lifetime action to set the pantheon_cache_default_max_age to less than the nonce lifetime. For example: do_action( 'pantheon_cache_nonce_lifetime' ); It’s important to wrap your do_action in the appropriate conditionals to ensure that the action is only called when necessary and not filtering the cache max age in cases when it’s not necessary. This might mean only running on certain pages or in certain contexts in your code. WP-CLI Commands This plugin implements a variety of WP-CLI commands. All commands are grouped into the wp pantheon cache namespace. $ wp help pantheon cache NAME wp pantheon cache DESCRIPTION Manage the Pantheon Advanced Page Cache. SYNOPSIS wp pantheon cache SUBCOMMANDS purge-all Purge the entire page cache. purge-key Purge one or more surrogate keys from cache. purge-path Purge one or more paths from cache. Use wp help pantheon cache to learn more about each command. Debugging By default, Pantheon’s infrastructure strips out the Surrogate-Key response header before responses are served to clients. The contents of this header can be viewed as Surrogate-Key-Raw by adding on a debugging header to the request. A direct way of inspecting headers is with curl -I. This command will make a request and show just the response headers. Adding -H "Pantheon-Debug:1" will result in Surrogate-Key-Raw being included in the response headers. The complete command looks like this: curl -IH "Pantheon-Debug:1" https://scalewp.io/ Piping to grep will filter the output down to just the Surrogate-Key-Raw header: curl -IH "Pantheon-Debug:1" https://scalewp.io/ | grep -i Surrogate-Key-Raw Tada! Emitted Keys and Purge Events Emitted Keys on Traditional Views Home / Emits surrogate keys: home, front, post- (all posts in main query) Single post /2016/10/14/surrogate-keys/ Emits surrogate keys: single, post- , post-user- , post-term- (all terms assigned to post) Author archive /author/pantheon/ Emits surrogate keys: archive, user- , post- (all posts in main query) Term archive /tag/cdn/ Emits surrogate keys: archive, term- , post- (all posts in main query) Day archive /2016/10/14/ Emits surrogate keys: archive, date, post- (all posts in main query) Month archive /2016/10/ Emits surrogate keys: archive, date, post- (all posts in main query) Year archive /2016/ Emits surrogate keys: archive, date, post- (all posts in main query) Search /?s= Emits surrogate keys: search, either search-results or search-no-results, post- (all posts in main query) Not found (404) Emits surrogate keys: 404 Emitted Keys on REST API Endpoints Posts /wp-json/wp/v2/posts emits surrogate keys: rest-post-collection, rest-post- /wp-json/wp/v2/posts/ emits surrogate keys: rest-post- Pages /wp-json/wp/v2/pages emits surrogate keys: rest-page-collection, rest-post- /wp-json/wp/v2/pages/ emits surrogate keys: rest-post- Categories /wp-json/wp/v2/categories emits surrogate keys: rest-category-collection, rest-term- /wp-json/wp/v2/categories/ emits surrogate keys: rest-term- Tags /wp-json/wp/v2/tags emits surrogate keys: rest-post_tag-collection, rest-term- /wp-json/wp/v2/tags/ emits surrogate keys: rest-term- Comments /wp-json/wp/v2/comments emits surrogate keys: rest-comment-collection, rest-comment-post- , rest-comment- /wp-json/wp/v2/comments/ emits surrogate keys: rest-comment-post- , rest-comment- Users /wp-json/wp/v2/users emits surrogate keys: rest-user-collection, rest-user- /wp-json/wp/v2/users/ emits surrogate keys: rest-user- Settings /wp-json/wp/v2/settings emits surrogate keys: rest-setting- Purge Events Different WordPress actions cause different surrogate keys to be purged, documented here. wp_insert_post / transition_post_status / before_delete_post / delete_attachment Purges surrogate keys: home, front, 404, post- , user- , term- , rest- -collection, rest-comment-post- Affected views: homepage, single post, any page with 404 header, any archive where post displays, author archive, term archive, REST API collection and resource endpoints clean_post_cache Purges surrogate keys: post- , rest-post- Affected views: single post, REST API resource endpoint created_term / edited_term / delete_term Purges surrogate keys: term- , post-term- , rest- -collection Affected views: term archive, any post where the term is assigned, REST API collection and resource endpoints clean_term_cache Purges surrogate keys: term- , rest-term- Affected views: term archive, REST API resource endpoint wp_insert_comment / transition_comment_status Purges surrogate keys: rest-comment-collection, rest-comment- Affected views: REST API collection and resource endpoints clean_comment_cache Purges surrogate keys: rest-comment- Affected views: REST API resource endpoint clean_user_cache Purges surrogate keys: user- , rest-user- Affected views: author archive, any post where the user is the author updated_option Purges surrogate keys: rest-setting- Affected views: REST API resource endpoint Surrogate Keys for taxonomy terms Setting surrogate keys for posts with large numbers of taxonomies (such as WooCommerce products with a large number of global attributes) can suffer from slower queries. Surrogate keys can be skipped for ‘product’ post types’ taxonomy terms (or any other criteria you see fit) with the following filter: function custom_should_add_terms($should_add_terms, $wp_query) { if ( $wp_query->is_singular( 'product' ) ) { return false; } return $should_add_terms; } add_filter('pantheon_should_add_terms', 'custom_should_add_terms', 10, 2); Other Filters pantheon_apc_disable_admin_notices Since 2.0.0, Pantheon Advanced Page Cache displays a number of admin notices about your current cache max age value. You can disable these notices with the pantheon_apc_disable_admin_notices filter. add_filter( 'pantheon_apc_disable_admin_notices', '__return_true' ); Alternately, the function callback is passed into the pantheon_apc_disable_admin_notices filter, allowing you to specify precisely which notice to disable, for example: add_filter( 'pantheon_apc_disable_admin_notices', function( $disable_notices, $callback ) { if ( $callback === '\\Pantheon_Advanced_Page_Cache\\Admin_Interface\\admin_notice_maybe_recommend_higher_max_age' ) { return true; } return $disable_notices; }, 10, 2 ); The above example would disable only the admin notice recommending a higher cache max age. Plugin Integrations Pantheon Advanced Page Cache integrates with WordPress plugins, including: WPGraphQL Contributing See CONTRIBUTING.md for information on contributing.

DietPress is a free WordPress speed optimization plugin with a built-in page cache. Page caching, browser caching, GZIP and Brotli compression, deferred JavaScript, critical CSS, image loading attributes, preloading, locally hosted Google Fonts and selective asset loading, all in one plugin and all free. And it goes further than a caching plugin: it also puts WordPress itself on a diet, switching off the features your site never uses. It pairs that with a clean, risk-based interface. Everything is configurable, the optimizations are already on by default, and nothing is hidden behind a paid tier. Activate it and your site is faster, or open the settings and tune every detail. By default WordPress loads functions, services and scripts that most sites do not need. They slow down loading times and consume hosting resources. DietPress lets you trim that fat and apply battle-tested performance tweaks, with a clear description of what each option does and what might break, organized by risk level so you always know what is safe. WHY CHOOSE DIETPRESS Page caching, for free. Serve anonymous visitors a copy stored on disk instead of building the page again. The feature people buy WP Rocket or a NitroPack subscription for, with no licence and no monthly fee. No drop-in, no changes to wp-config.php. Unlike WP Super Cache or W3 Total Cache, DietPress installs no advanced-cache.php and never edits wp-config.php. Switching it off leaves your site exactly as it was, with nothing orphaned behind. It tells you why. Most cache plugins leave you guessing when nothing is cached. DietPress reports its own status, tests itself against your home page, and names the exact reason a page was skipped. WooCommerce-safe by design. Carts, checkout, my account and any visitor carrying a cart cookie always get the live site, so nobody ever sees somebody else’s basket. Diet as well as speed. Where Perfmatters focuses on disabling scripts, DietPress covers that ground and adds page caching, critical CSS, local Google Fonts and a dashboard, admin and email cleanup, in one plugin. Light on your server. No account, no external service, no telemetry, no upsell nags. Everything runs on your own hosting. WHAT THE PAGE CACHE DOES TO YOUR RESPONSE TIME Measured on a WordPress 7.0 install with GeneratePress, WooCommerce and a 76 product catalogue, PHP 8.5, taking the median of 15 requests per URL. Your own hosting will give different figures, but the shape of the result will not change. Server response time, the same pages with the page cache off and on: Home page – 52.7 ms without, 15.1 ms with, 71% faster WooCommerce shop – 45.4 ms without, 14.8 ms with, 67% faster A 110 KB article – 43.0 ms without, 15.1 ms with, 65% faster A 98 KB page – 41.0 ms without, 14.9 ms with, 64% faster A product category – 41.3 ms without, 15.1 ms with, 63% faster The interesting part is not the percentage, it is that the cached figure barely moves. Serving a stored file costs the same whether the page was cheap or expensive to build, so the saving grows with the size of your site rather than with the power of your server. The heaviest page in the test is the one that gained most. It also changes how much traffic your hosting can take at once. In the same test the server went from serving about 40 visits a second to more than 210, five times as many, on exactly the same plan. That is what keeps a small site standing up when one of your posts does well. TWO THINGS IN ONE PLUGIN 1. Performance optimizations (on by default) Automatic Critical CSS inlined in the head (optional experimental deferral of non-critical CSS) JavaScript defer parsing with smart dependency handling Image loading attributes safety net: lazy loading, decoding=async and fetchpriority for images that bypass core Automatic image dimensions for better CLS scores (including picture elements) Resource hints: preconnect and DNS prefetch for common third-party origins Theme stylesheet, critical fonts and logo preloading for a faster LCP Google Fonts display=swap Google Fonts local hosting: serve the fonts your theme uses from your own server, GDPR-friendly with a silent fallback to the Google CDN (opt-in) Selective third-party loading: WooCommerce, Contact Form 7, block library, Slider Revolution, TablePress, Smash Balloon, Formidable Forms and Everest Forms assets only load where they are used (opt-in) RSS feed optimization (cache headers and item limit) Server rules in .htaccess: browser caching with a configurable lifetime for media, for styles and scripts and for fonts, GZIP and Brotli compression, immutable cache headers, CORS for fonts and keep-alive (master switch plus per-feature toggles) Database maintenance: daily expired-transient cleanup and safe query optimizations Page cache: store each page on disk and serve it to anonymous visitors without building it again, with automatic purging, gzip precompression and a status panel that says whether it is working (opt-in, in its own tab) 2. Put WordPress on a diet (risk-based, opt-in) Light (safe for any site): emojis, RSD/WLW tags, shortlinks, self-pingbacks, comment pagination, and more Moderate (evaluate first): oEmbed, jQuery Migrate, Dashicons on the frontend, Global Styles and Duotone, remote block patterns, avatars and Gravatar, comment threading, and more Strict (site-specific): granular RSS feed control, Heartbeat API mode, post revisions and autosave, disable comments, XML sitemap, native lazy loading/fetchpriority, content types, selective loading for WooCommerce, Contact Form 7, block assets, Slider Revolution, TablePress, Smash Balloon, Formidable Forms and Everest Forms, and more Widgets: dashboard widgets (including third-party ones from Yoast, WooCommerce, Elementor, Jetpack, Wordfence, Rank Math, Gravity Forms), classic sidebar widgets, block-editor widgets and the Customizer Emails: silence the automatic emails WordPress sends on its own, grouped by area: auto-update results for core, plugins and themes (plus the new-version notice), comment moderation and new-comment notices, and new user, password and email-change notices, plus toggles for the admin email verification prompt and post-by-email. Every option is off by default, and critical notices such as a failed core update are always kept SCALE, PROFILES AND ANALYZER Savings indicator: HTTP requests removed, CSS/JS saved and active optimizations at a glance Quick profiles: Personal Blog, WooCommerce Store, Landing Page and Maximum Cleanup Site analyzer: personalized recommendations based on your active plugins and content, page cache included Import and export your whole configuration as a JSON file COMPATIBILITY AND EXTENSIBILITY The plugin includes filters for developers: dietpress_critical_css – Customize the inline critical CSS dietpress_critical_css_handles – Define which CSS handles are critical dietpress_skip_defer_script_handles – Opt scripts out of the JavaScript defer dietpress_skip_defer_style_handles – Opt stylesheets out of the CSS deferral dietpress_preconnect_hints – Customize preconnect origins dietpress_dns_prefetch_domains – Customize DNS prefetch domains dietpress_critical_fonts – Define critical fonts to preload dietpress_exclude_local_fonts – Exclude Google Fonts stylesheets from local hosting dietpress_selective_{module}_has_content – Mark a page as showing the content of a selective loading module, so its assets are kept. The module is wc, cf7, formidable, everest_forms or revslider dietpress_selective_{module}_styles / dietpress_selective_{module}_scripts – Adjust the handles removed by each module dietpress_selective_page_hides_content – Mark a page as rendering content the content scan cannot reach, so no module removes anything (this is what handles Elementor) dietpress_selective_is_wc_page – Override the WooCommerce page detection of selective loading dietpress_selective_wc_keep_cart_fragments – Keep the cart fragments script when your theme has a hand-coded mini-cart dietpress_selective_cf7_has_form – Mark pages that load a Contact Form 7 form dynamically dietpress_selective_blocks_dequeue – Override the block library dequeue decision dietpress_selective_everest_forms_dequeue_dashicons – Keep Dashicons when another plugin enqueues it directly dietpress_native_sitemap_in_use – Tell DietPress your plugin builds on the native WordPress sitemap, so the option that removes it becomes unavailable dietpress_cache_bypass – Keep the current page out of the page cache dietpress_cache_bypass_cookies – Adjust the cookie name prefixes that make a visitor uncacheable dietpress_cache_ignored_params – Adjust the query parameters that do not change the page dietpress_cache_exclude_urls – Adjust the excluded URL patterns dietpress_cache_post_urls – Adjust the URLs purged along with a post Compatible with: Well-coded themes and page builders (Divi, Elementor, Beaver Builder, Bricks Gutenberg) Cache plugins (WP Rocket, LiteSpeed Cache, W3 Total Cache, WP Super Cache, etc.). The one exception is the optional page cache module, which will not run beside another page cache and says so; everything else in DietPress works alongside them as it always has Security plugins (DietPress focuses on performance and deliberately leaves security to them; we recommend our free Vigilant) CDNs (Cloudflare, StackPath, KeyCDN, etc.) thanks to CORS and Vary headers WordPress Multisite (except the optional page cache module, which does not support it yet) HOW TO VERIFY THE OPTIMIZATIONS Cache rules: check your .htaccess for a block marked # BEGIN DietPress with immutable Cache-Control headers Logo preload: view page source and look for pointing to your logo Critical CSS: view source and look for in the head Compression: test at giftofspeed.com/gzip-test Always measure with tools like Google PageSpeed, GTMetrix or WebPageTest, and run each test at least twice to account for caching. Support Need private support or custom development? Do you need one-on-one help, priority troubleshooting, or a custom feature, integration, or tweak built specifically for your site? I offer private support and custom development. Just contact me and tell me what you need. Need help or have suggestions? Official website WordPress support forum YouTube channel Documentation and tutorials Love the plugin? Please leave us a 5-star review and help spread the word! About AyudaWP We are specialists in WordPress security, SEO, AI and performance optimization plugins. We create tools that solve real problems for WordPress site owners while maintaining the highest coding standards and accessibility requirements.