iispeed.com

What It Is

IISpeed is a native C++ PageSpeed optimization module from We-Amp B.V. for Microsoft IIS. Its goal is to automatically rewrite web resources during the response stage, improving bandwidth usage, latency, and Core Web Vitals. It has now been migrated to the IIS port of mod_pagespeed 1.1: existing IISpeed installations can still run, but new features, bug fixes, and security patches will go into 1.1.

Core Capabilities

Its main value lies in “transparent optimization” for legacy IIS applications: classic ASP.NET, ASP.NET MVC, Classic ASP, SharePoint, and PHP/ColdFusion on Windows can gain image, CSS, and JS optimization without refactoring or adding a build pipeline. The documented features include JPEG/PNG recompression, WebP/AVIF content negotiation, automatic resizing to rendered dimensions, Critical CSS inlining, CSS deferral, lazy loading for images and iframes, deferring non-critical JavaScript, and server-side caching of multiple resource versions. This is especially useful for WebForms, SharePoint, or traditional enterprise sites that lack a modern frontend pipeline.

Deployment, Ecosystem, and Pricing

IISpeed/mod_pagespeed 1.1 runs as a native IIS module and can be installed on Windows Server, with signed MSI packages and checksum files provided. For ASP.NET Core, WeAmp.PageSpeed.AspNetCore is available as a NuGet middleware package; the documentation says it supports .NET 8/.NET 9, but it is still in Preview. New sales of IISpeed have been discontinued, and there is no current price list. Existing license holders can migrate to mod_pagespeed 1.1 for free by emailing their license key; processing is typically manual and takes 1-2 business days. New purchases should refer to the mod_pagespeed 1.1 pricing page.

Pros, Cons, and Who It’s For

The advantage is that it can cover multiple optimizations affecting LCP, CLS, and INP without requiring changes to business code. Its FAQ also gives fairly detailed explanations of issues such as URL length, cache purging, permissions, Plesk, first requests not being fully optimized, and the roughly 10ms CPU overhead. The downsides are that the product branding is in transition, IISpeed itself is no longer sold to new customers, and license migration depends on manual handling. In addition, this kind of server-side rewriting requires operations teams to understand IIS permissions, registry limits, and caching mechanisms. It is best suited to teams that still rely heavily on IIS and traditional .NET and cannot modernize their frontend in the short term.

Access from China

The available information does not mention network access from mainland China, payment support, or local support, so its accessibility should be considered unknown. For China-based sites with high availability requirements, it is also worth evaluating domestic CDN image optimization, edge caching, Nginx/OpenResty optimization pipelines, or self-hosted mod_pagespeed-related solutions on controlled intranet or cloud infrastructure.