Technical insights on web performance, automatic optimization, and the engineering behind mod_pagespeed.https://modpagespeed.com/en-usSat, 10 Oct 2026 00:00:00 GMThttps://modpagespeed.com/blog/pagespeed-installed-base-2026/https://modpagespeed.com/blog/pagespeed-installed-base-2026/HTTP Archive data on the PageSpeed installed base in 2026: adoption since 2020, versions, servers, networks, and what no longer receives fixes.Sat, 10 Oct 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/cyclone-kv-cache-tier-vs-lmdb/https://modpagespeed.com/blog/cyclone-kv-cache-tier-vs-lmdb/How Cyclone became an LLM KV-cache offload tier: eight rounds against LMDB and file-per-block, from 0.06 GB/s cold reads to ahead of LMDB.Thu, 08 Oct 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/mod-pagespeed-2-1-one-product-again/https://modpagespeed.com/blog/mod-pagespeed-2-1-one-product-again/The mod_pagespeed lineage and the ModPageSpeed 2.0 engine converge into one open-source product: the module you know plus an optimizer worker. Apache-2.0.Thu, 17 Sep 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/cyclone-cache-vs-file-cache-benchmark/https://modpagespeed.com/blog/cyclone-cache-vs-file-cache-benchmark/Cache benchmark: Cyclone (memory-mapped, in-process RAM tier) vs the classic file-per-entry cache, across concurrency, traffic, latency tails and eviction.Sat, 04 Jul 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/agentic-web-at-the-origin/https://modpagespeed.com/blog/agentic-web-at-the-origin/The agentic web creates four origin problems: identity, economics, what to serve, provenance. Where to solve them, and why on your own servers.Mon, 22 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/pay-per-crawl-at-the-origin/https://modpagespeed.com/blog/pay-per-crawl-at-the-origin/mod_pagespeed 2.1 ships an experimental, off-by-default RSL-CAP gate for nginx: check License capability tokens and refuse unauthorized AI crawlers.Mon, 22 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/preserve-content-credentials-c2pa/https://modpagespeed.com/blog/preserve-content-credentials-c2pa/mod_pagespeed detects C2PA Content Credentials manifests and keeps image provenance instead of stripping it when optimizing. On by default in both parts.Mon, 22 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/serve-markdown-to-ai-agents/https://modpagespeed.com/blog/serve-markdown-to-ai-agents/The mod_pagespeed 2.1 worker serves a markdown variant on Accept: text/markdown and builds /llms.txt from your sitemap. Experimental, off by default.Mon, 22 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/verify-ai-crawlers-web-bot-auth/https://modpagespeed.com/blog/verify-ai-crawlers-web-bot-auth/mod_pagespeed 2.1 ships an nginx Web Bot Auth verifier: it checks RFC 9421 signatures and labels requests in $x_verified_bot. Observe-only, off by default.Mon, 22 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/air-gapped-headless-fetch-ssrf-pinning/https://modpagespeed.com/blog/air-gapped-headless-fetch-ssrf-pinning/SSRF protection for headless rendering: the optimizer worker forces Chrome offline and routes subresources via an IP-pinned fetch, checked per redirect.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/cache-key-url-normalization-tracking-params/https://modpagespeed.com/blog/cache-key-url-normalization-tracking-params/Strip tracking parameters to stop cache fragmentation: mod_pagespeed 2.1 normalizes URLs before keying, drops UTM params, sorts the query, aliases hosts.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/default-cache-ttl-heuristic-freshness/https://modpagespeed.com/blog/default-cache-ttl-heuristic-freshness/Default cache TTL with no Cache-Control: per-content-type heuristic TTLs, RFC 9111 Age adjustment and the shared-vs-private split in mod_pagespeed 2.1.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/headless-lcp-cls-measurement/https://modpagespeed.com/blog/headless-lcp-cls-measurement/Headless LCP and CLS measurement in mod_pagespeed 2.1: the optimizer worker's PerformanceObservers capture the LCP element and shifts to drive preloads.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/proactive-variant-generation-cache-warmup/https://modpagespeed.com/blog/proactive-variant-generation-cache-warmup/How the mod_pagespeed 2.1 worker warms hot URLs: nginx flags a hot URL and the worker pre-builds the whole image variant matrix instead of one per request.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/remove-unused-javascript-chrome-coverage/https://modpagespeed.com/blog/remove-unused-javascript-chrome-coverage/A headless Chrome V8 coverage pass measures which JavaScript runs before first paint, so the mod_pagespeed 2.1 worker can defer the scripts that never run.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/safe-javascript-minification-semicolon-insertion/https://modpagespeed.com/blog/safe-javascript-minification-semicolon-insertion/Safe JavaScript minification means parsing, not stripping whitespace: semicolon insertion, regex-vs-divide and a fail-safe that ships the original as is.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/serve-markdown-to-ai-crawlers-llms-txt/https://modpagespeed.com/blog/serve-markdown-to-ai-crawlers-llms-txt/How to serve markdown to AI crawlers on the same URL via Accept: text/markdown, synthesize /llms.txt from the sitemap, and honor AI opt-out directives.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/server-injected-resource-hints-speculation-rules/https://modpagespeed.com/blog/server-injected-resource-hints-speculation-rules/How a proxy generates server-injected resource hints: speculation-rules prefetch derived from real traffic, priority-bucketed preconnect, font preload.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/ssimulacra2-image-quality-verification/https://modpagespeed.com/blog/ssimulacra2-image-quality-verification/How mod_pagespeed 2.1 scores encoded images against a SSIMULACRA2 target in the optimizer worker and re-encodes until the result clears tolerance.Sun, 14 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/cache-key-derivation-and-alternate-fallback/https://modpagespeed.com/blog/cache-key-derivation-and-alternate-fallback/How cache key derivation in mod_pagespeed 2.1 hashes host plus URL into one key and scores stored variants in one selector pass instead of probing keys.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/cache-mode-safety-must-revalidate-vs-aggressive/https://modpagespeed.com/blog/cache-mode-safety-must-revalidate-vs-aggressive/Why must-revalidate, not max-age, is the real safety net in mod_pagespeed 2.1, and when aggressive TTLs with stale-if-error are the right call.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/conditional-revalidation-304-vs-active-purge/https://modpagespeed.com/blog/conditional-revalidation-304-vs-active-purge/When a 304 ETag round-trip beats PURGE and keeps optimized AVIF and WebP variants on an HTML-only deploy with no rebuild.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/critical-css-beacon-to-headless-history/https://modpagespeed.com/blog/critical-css-beacon-to-headless-history/How critical CSS extraction works without a build step: the original beacon model, why CDNs broke it, and how 2.0 moved to heuristics + headless Chrome.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/css-cache-inlining-for-coverage-api/https://modpagespeed.com/blog/css-cache-inlining-for-coverage-api/How mod_pagespeed 2.1 feeds the Chrome Coverage API critical CSS: the worker inlines cached stylesheets into a network-blocked sandbox to see real usage.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fire-and-forget-worker-ipc/https://modpagespeed.com/blog/fire-and-forget-worker-ipc/mod_pagespeed 2.1 keeps optimization off the nginx request path: a small notification to the worker, no reply, so a cache miss stays cheap and none waits.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/flatten-css-imports-edge-cases/https://modpagespeed.com/blog/flatten-css-imports-edge-cases/Why flattening CSS @import rules is harder than concatenation: media intersection, @charset aborts, url() rebasing, and the CssFlattenMaxBytes cap.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/image-content-classification-and-denoise/https://modpagespeed.com/blog/image-content-classification-and-denoise/Content-aware image optimization classifies each image and denoises noisy sources before encoding, so photos, screenshots and logos get the right codec.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/memory-mapped-cache-zero-copy-serving/https://modpagespeed.com/blog/memory-mapped-cache-zero-copy-serving/How mod_pagespeed 2.1 shares one memory-mapped cache between nginx and the worker: large hits zero-copy via sendfile, small ones with a single copy.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/mod-pagespeed-content-security-policy/https://modpagespeed.com/blog/mod-pagespeed-content-security-policy/Does mod_pagespeed break a strict Content-Security-Policy? Where rewriting collides with a CSP, feature by feature, and how HonorCsp keeps pages compliant.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/sentinel-cache-keys-and-103-early-hints/https://modpagespeed.com/blog/sentinel-cache-keys-and-103-early-hints/How the mod_pagespeed 2.1 worker precomputes 103 Early Hints preloads that nginx serves from cache, stored under reserved sentinel keys beside each URL.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/single-url-cache-purge-optimizing-proxy/https://modpagespeed.com/blog/single-url-cache-purge-optimizing-proxy/Purging one URL in mod_pagespeed 2.1 touches more than one cache entry: the fan-out problem, the 1.x lookup-time design, and why the worker deletes now.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/svg-auto-vectorization/https://modpagespeed.com/blog/svg-auto-vectorization/Raster to SVG auto-vectorization in mod_pagespeed 2.1: the optimizer worker traces logos and icons with VTracer, collapsing the variant matrix into one.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/template-hashing-critical-css-reuse/https://modpagespeed.com/blog/template-hashing-critical-css-reuse/How the mod_pagespeed 2.1 worker hashes a page template so critical CSS is computed once and reused across every URL sharing it, with queue dedup.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/visual-regression-gating-optimizations/https://modpagespeed.com/blog/visual-regression-gating-optimizations/The mod_pagespeed 2.1 worker pixel-diffs the rendered above-fold before caching a headless critical-CSS variant; if it looks different, it is discarded.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/wordpress-server-side-page-cache-plugin/https://modpagespeed.com/blog/wordpress-server-side-page-cache-plugin/How a WordPress server-side page cache plugin sets Cache-Control on anonymous pages and purges the mod_pagespeed cache on publish, not caching in PHP.Sat, 13 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/search-console-ai-performance-report-vs-page-speed/https://modpagespeed.com/blog/search-console-ai-performance-report-vs-page-speed/The Search Console AI performance report measures your visibility in AI Overviews and AI Mode, not how fast your pages load. The difference, explained.Tue, 09 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/avif-vs-webp-2026/https://modpagespeed.com/blog/avif-vs-webp-2026/AVIF beats WebP on size but is slower to encode. Serve AVIF, WebP or the original per request off the Accept header instead of one format for everyone.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/learned-quality-prediction/https://modpagespeed.com/blog/learned-quality-prediction/One perception-based quality knob: a trained model predicts JPEG, WebP and AVIF encoding parameters per image in microseconds. No per-codec tuning.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/nginx-image-optimization-module/https://modpagespeed.com/blog/nginx-image-optimization-module/A native nginx module that transcodes images to WebP and AVIF on serve, negotiates on Accept and caches the variant. Signed apt/yum packages, no compiling.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/ngx-pagespeed-wont-build-modern-nginx/https://modpagespeed.com/blog/ngx-pagespeed-wont-build-modern-nginx/Why upstream ngx_pagespeed won't compile on nginx 1.25+ (sys_siglist, glibc, OpenSSL 3, toolchain drift) — and the prebuilt module to install instead.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/reduce-ttfb-server-layer-2026/https://modpagespeed.com/blog/reduce-ttfb-server-layer-2026/Reduce TTFB on nginx: split origin compute, network, and cache, then fix keep-alive, HTTP/2 or HTTP/3, TLS resumption, and variant-aware caching.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/self-hosted-image-optimization/https://modpagespeed.com/blog/self-hosted-image-optimization/Image SaaS bills per transformation and per GB of egress. Self-hosted optimization transcodes WebP/AVIF on your servers: no per-transformation cost.Sat, 06 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/content-hash-urls/https://modpagespeed.com/blog/content-hash-urls/A content hash in a .pagespeed. URL gives year-long caching with automatic cache busting, years before webpack contenthash. Plus data-pagespeed-url-hash.Fri, 05 Jun 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/can-ai-read-your-website/https://modpagespeed.com/blog/can-ai-read-your-website/40% of the top 1,000 sites serve almost nothing to non-JavaScript AI crawlers: ChatGPT, Perplexity and Claude see an empty page. The data, and the fix.Thu, 28 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/aspnet-core-image-optimization-c-sharp/https://modpagespeed.com/blog/aspnet-core-image-optimization-c-sharp/Serve WebP and AVIF from ASP.NET Core with no controller or Razor changes: WeAmp.PageSpeed middleware negotiates on Accept, sizes images, preloads LCP.Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-inp-aspnet-core-2026/https://modpagespeed.com/blog/fix-inp-aspnet-core-2026/How to fix INP on ASP.NET Core: Razor + jQuery responds well to bundling and the WeAmp.PageSpeed middleware; Blazor Server INP is architectural (WASM).Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/google-dl-ssl-mod-pagespeed-download/https://modpagespeed.com/blog/google-dl-ssl-mod-pagespeed-download/The dl-ssl.google.com mod_pagespeed .deb is the last stable build, 1.13.35.2 (2018), with years of unpatched CVEs. Get the maintained download instead.Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/mod-pagespeed-deprecated-2026/https://modpagespeed.com/blog/mod-pagespeed-deprecated-2026/Yes, mod_pagespeed 1.13.35.2 is deprecated: the binaries run but have had no security updates in years. What to use on Apache, nginx, IIS and ASP.NET Core.Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/run-with-docker-compose/https://modpagespeed.com/blog/run-with-docker-compose/A working docker-compose.yml for ModPageSpeed 2.0 on nginx: worker + interceptor + shared Cyclone cache volume. Verify with curl, done.Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/server-side-critical-css-nginx/https://modpagespeed.com/blog/server-side-critical-css-nginx/Extract and inline critical CSS at the nginx layer for any backend: PHP, Rails, Django, ASP.NET, Go. No WordPress plugin, headless browser or Node build.Wed, 20 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-cls-aspnet-core-2026/https://modpagespeed.com/blog/fix-cls-aspnet-core-2026/How to fix CLS on ASP.NET Core: pre-size async view components, persist image dimensions, reserve banner space, rewrite img tags via middleware.Tue, 19 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-lcp-aspnet-core-2026/https://modpagespeed.com/blog/fix-lcp-aspnet-core-2026/Fix LCP on ASP.NET Core: async view components, immutable cache headers, deferred JS and the WeAmp.PageSpeed middleware, for Razor Pages, MVC and Blazor.Mon, 18 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/mod-pagespeed-1-1-release/https://modpagespeed.com/blog/mod-pagespeed-1-1-release/mod_pagespeed 1.15 ships 765 merges since 1.13.35.2: image-decoder hardening, a full sanitizer matrix, current dependencies and the IIS port in the tree.Sun, 17 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-inp-nginx-2026/https://modpagespeed.com/blog/fix-inp-nginx-2026/How to fix INP on nginx, CMS-agnostic. Server-layer JS minification helps if your JS is bloated; if your stack is already lean, the wins are upstream.Thu, 14 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-cls-nginx-2026/https://modpagespeed.com/blog/fix-cls-nginx-2026/Fix CLS on nginx sites: add width and height to img tags with ngx_pagespeed (mod_pagespeed 2.1), add a CSS aspect-ratio backstop, set sizes at build.Tue, 12 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-lcp-nginx-2026/https://modpagespeed.com/blog/fix-lcp-nginx-2026/How to fix LCP on nginx: HTTP/2, gzip_static, TLS resumption and the mod_pagespeed rewriter. Stack-agnostic LCP fixes that work behind any backend.Thu, 07 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-inp-magento-2026/https://modpagespeed.com/blog/fix-inp-magento-2026/INP on Magento 2 lives in KnockoutJS and RequireJS, so theme architecture (Hyvä) moves it, not a server rewriter. What mod_pagespeed can and cannot do.Tue, 05 May 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-cls-magento-2026/https://modpagespeed.com/blog/fix-cls-magento-2026/Fix CLS on Magento 2 product pages: stop Fotorama gallery jumps, pre-size the mini-cart and private-content blocks, write img dimensions at the server.Thu, 30 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-lcp-magento-2026/https://modpagespeed.com/blog/fix-lcp-magento-2026/How to fix LCP on Magento: tame the RequireJS waterfall, regenerate catalog images, inline critical CSS at the server. Step-by-step for Magento 2 in 2026.Tue, 28 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-inp-woocommerce-2026/https://modpagespeed.com/blog/fix-inp-woocommerce-2026/How to fix INP on WooCommerce: server-layer JS minification reduces the parse cost, but cart and variation handlers are architectural.Thu, 23 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-cls-woocommerce-2026/https://modpagespeed.com/blog/fix-cls-woocommerce-2026/How to fix CLS on WooCommerce: stop the gallery shift, lock variation swap dimensions, reserve cross-sell space, and rewrite img tags at the server.Tue, 21 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-lcp-woocommerce-2026/https://modpagespeed.com/blog/fix-lcp-woocommerce-2026/Fix LCP on WooCommerce: shrink the product gallery, drop cart-fragments on non-shop pages, and rewrite catalog images at the server with mod_pagespeed.Thu, 16 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-inp-wordpress-2026/https://modpagespeed.com/blog/fix-inp-wordpress-2026/How to fix INP on WordPress: diagnose the responsible interaction, defer non-critical JS at the server layer, then trim plugin handlers and jQuery.Tue, 14 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-cls-wordpress-2026/https://modpagespeed.com/blog/fix-cls-wordpress-2026/How to fix CLS on WordPress: diagnose the shifts, set width/height on every image at the server layer, lock down fonts, reserve banner space.Fri, 10 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/fix-lcp-wordpress-2026/https://modpagespeed.com/blog/fix-lcp-wordpress-2026/How to fix LCP on WordPress: diagnose the hero, inline critical CSS at the server, convert JPEG to WebP, and verify in Search Console. Step-by-step, 2026.Wed, 08 Apr 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/mod-pagespeed-alternatives/https://modpagespeed.com/blog/mod-pagespeed-alternatives/Google mod_pagespeed and ngx_pagespeed are no longer actively developed. mod_pagespeed 2.1 is the maintained continuation. Here is how the paths compare.Mon, 16 Mar 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/aspnet-core-middleware/https://modpagespeed.com/blog/aspnet-core-middleware/Run the mod_pagespeed 2.1 optimization pipeline as ASP.NET Core middleware from NuGet: image transcoding, critical CSS and cache serving in 2 lines of C#.Thu, 12 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/migrating-from-1x/https://modpagespeed.com/blog/migrating-from-1x/Migrating from the archived mod_pagespeed 1.13.x or ngx_pagespeed: directive mapping, image-format checks, a verification checklist, and the 2.1 path.Tue, 10 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/critical-css-heuristics/https://modpagespeed.com/blog/critical-css-heuristics/How the mod_pagespeed 2.1 optimizer worker inlines critical CSS two ways: static heuristics in under 5ms per page, or an optional headless-Chrome path.Sun, 08 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/economics-of-image-optimization/https://modpagespeed.com/blog/economics-of-image-optimization/Image CDNs run $35 to $3,500/mo as traffic grows; self-hosted mod_pagespeed 2.1 stays flat. Break-even is ~100 to 170K requests/mo. The 2026 cost model.Sat, 07 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/save-data-bandwidth/https://modpagespeed.com/blog/save-data-bandwidth/How mod_pagespeed 2.1 reads the Save-Data request header to serve lighter image variants: a 30-50% bandwidth cut on top of format and viewport sizing.Fri, 06 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/benchmarking-real-numbers/https://modpagespeed.com/blog/benchmarking-real-numbers/Measured ModPageSpeed 2.0 results on e-commerce, blog, news and portfolio sites: WebP/AVIF savings and LCP, FCP, CLS and Lighthouse gains, 3G to broadband.Thu, 05 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/viewport-aware-image-optimization/https://modpagespeed.com/blog/viewport-aware-image-optimization/Serve WebP and AVIF automatically on nginx, self-hosted. The mod_pagespeed 2.1 worker decodes each image once and builds up to 37 responsive variants.Tue, 03 Feb 2026 00:00:00 GMTOtto van der Schaafhttps://modpagespeed.com/blog/why-i-rebuilt-mod-pagespeed/https://modpagespeed.com/blog/why-i-rebuilt-mod-pagespeed/The story behind ModPageSpeed 2.0: why mod_pagespeed stopped being developed, what was kept from PSOL, and how a new architecture replaced RewriteDriver.Sun, 01 Feb 2026 00:00:00 GMTOtto van der Schaaf