TL;DR: WordPress 7.1 processes images in the browser to make uploads more reliable. It does not optimize your images the way a dedicated plugin does. If page speed matters to you, you still need an image optimization plugin.
One of the headline features in WordPress 7.1 is client-side media processing. Your browser now handles image compression and thumbnail generation before the file ever reaches your server.
It's a genuinely useful engineering upgrade. It's just not the same thing as image optimization, and it's not a replacement for an image optimization plugin.
What actually changed in WordPress 7.1
This release fixes a real, long-standing problem. Uploading a large photo could blow past the host's PHP memory limit or simply time out, especially on shared hosting. WordPress 7.1 solves that by moving the work into the browser.
Compression, thumbnail generation, and EXIF rotation now run in the browser through wasm-vips, a WebAssembly build of libvips, instead of relying only on the server's GD or Imagick setup. HEIC, AVIF, and HDR images are decoded and handled automatically, uploads retry if the connection drops, and there's a new media editor for cropping, flipping, rotation, and metadata.
None of that is a gimmick. But "processes your image without crashing the server" and "optimizes your image" are two different claims, and WordPress 7.1 really only delivers on the first one.
Where WordPress 7.1 stops short
It's one setting for every image. The same default quality applies across the board. There's no per-image analysis of how much each picture can actually afford to lose.
It doesn't touch your existing library. Only new uploads go through the new pipeline. Everything already in your Media Library stays as it was.
It depends on the browser. Client-side processing currently needs a recent Chromium-based browser, like Chrome or Edge. On Firefox, Safari, or older browsers, WordPress falls back to the same server-side pipeline it has always used.
There's no delivery layer. WordPress 7.1 won't automatically generate WebP or AVIF versions and serve the right one to each visitor, and it won't put your images on a CDN.
There's no undo button. Once an image is processed and the sub-sizes are generated, that's what you're serving. There's no built-in way to dial the compression back if an image doesn't hold up.
Why "smaller file" isn't "optimized image"
A fixed quality setting is a blunt instrument. It doesn't know or care what's in the image. Apply one number to everything, and you leave savings on the table for the simple images while risking visible quality loss on the complex ones.
That's the gap a dedicated image optimization plugin is built to close. A plugin like ShortPixel doesn't apply one quality value to every file. It checks each image against the original using SSIM (structural similarity) and keeps optimizing until it finds the smallest file that's still visually indistinguishable from the original.
This is exactly what core WordPress doesn't do, and it's where most of the real savings come from.
Why you still need an image optimization plugin
If WordPress 7.1 is the only tool in your stack, you're missing:
- Bulk optimization of your existing Media Library, not just new uploads
- Automatic WebP and AVIF delivery, with the right format for each browser
- CDN-backed delivery, with images served from a location close to each visitor
- Lossy, Glossy, and Lossless modes you actually control
- PDF compression, which core WordPress doesn't touch
- A one-click way to restore originals
- Consistent results regardless of the browser
Every one of these affects how fast your pages load. None of them come with WordPress 7.1.
So, should you keep your image optimization plugin?
Yes. WordPress 7.1 does not replace it.
WordPress 7.1's client-side processing mainly solves a server-side problem: memory limits, timeouts, and upload reliability. It isn't designed to solve the optimization problem, which is getting every image, old and new, as small as possible without anyone noticing.
The best setup is to use both. Update to WordPress 7.1 for the smoother upload pipeline, and run a dedicated image optimization plugin for adaptive compression, next-gen formats, and CDN delivery. One handles the plumbing. The other actually optimizes your images.
If you don't have an image optimization plugin yet, now is a good time to add one.
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