Image optimization

Silktide downloads the images on your pages and tests whether they could be made meaningfully smaller without visibly changing them. Images that could be reduced are reported along with the possible saving, so you can prioritize the biggest wins.

Why this matters

Images are usually most of a web page's weight, so they are usually the largest single performance opportunity. Oversized images make pages slower to appear, which measurably increases abandonment - especially on mobile connections - and costs your visitors real bandwidth and battery. Page speed also feeds into search ranking through .

Unlike most performance work, image optimization rarely involves trade-offs: a properly compressed image looks the same and behaves the same. It is close to free performance.

How to fix it

Compress the reported images. Almost every image tool can do this on export; photographs should generally be JPEG at around 85% quality, which saves a lot of file size with minimal visible loss.
Use the right format: JPEG (or WebP/AVIF) for photographs; PNG or SVG for logos, icons, and other flat-color artwork. Modern formats like WebP and AVIF beat both where your platform supports them.
Automate it. Most , build pipelines, and can compress and convert images on upload or on delivery - fixing the pipeline stops the problem recurring.
Serve images at the size they are displayed, using responsive images (srcset) rather than shipping one huge image to every device:

<img src="hero-800.jpg"
     srcset="hero-800.jpg 800w, hero-1600.jpg 1600w"
     sizes="(max-width: 800px) 100vw, 800px"
     alt="Vineyard at sunset">

How Silktide tests this

Collect the images each page actually loads.
Re-compress each image with techniques appropriate to its format: progressive JPEG at 85% quality, lossy and lossless PNG recompression, SVG , and GIF re-optimization.
Compare the best result against the original. An image is reported only when the saving is meaningful: more than 20% smaller and more than 40 KB saved.
Report the possible reduction for each image, so the largest savings stand out.

Troubleshooting

The image already looks compressed

The reported saving is measured, not estimated - Silktide actually produced a smaller file. Common reasons an apparently optimized image still loses 20% include embedded metadata, non-progressive JPEG encoding, and PNGs used for photographs.

We use a CDN that optimizes images

Silktide tests what the page really served, so if a reported image passed through your CDN, that optimization either wasn't applied or wasn't sufficient. Check the CDN's settings for the affected paths or formats.

The saving seems small

Images within 20% or 40 KB of optimal are not reported. If a reported saving looks minor, remember it applies on every page view of every visitor.