Slipcase: from a 46 to a 91 performance score by fixing the images
Slipcase's SEO team wanted faster pages. Images were 60–70% of every download, so we put FileJet — our image and asset optimisation service — in front of them. Time to interactive fell from 16.3 s to 4.2 s in one release.
- Service
- Development
- Industry
- Insurance media
- Client
- Slipcase ↗
- Year
- 2019
Slipcase, the news and insight platform for the (re)insurance industry, is an image-heavy site by design — full-bleed photographic headers on every page, including on phones. Images made up 60–70% of the download size, and even with a regular CDN and pre-processed assets the home page scored 46 on Google's performance audit and took 16.3 seconds to become interactive.
We deployed FileJet, Everlution's asset-optimisation proxy, in front of the site. FileJet reads the headers each browser and device sends, converts every image to the best format and size that device supports, and serves it from the nearest of 240+ edge locations. Other assets were minified and compressed in the same release; the design was not touched.
Measured with Google's audit tool and the FileJet inspector four days apart — home page performance 46 → 91, accessibility 67 → 94, best practices 93 → 100, SEO 90 → 100, time to interactive 16.3 s → 4.2 s, image weight 2.41 MB → 0.7 MB. Publication and article pages lost more than half their total weight.
The situation
Slipcase brings news, insights and perspectives to people across the (re)insurance industry, and it looks the part: every page opens with a large, high-quality photographic header. Those headers are the brand — and they were also the problem. Images accounted for 60–70% of the page download, and the SEO team asked for a page-speed improvement to lift the site’s search rating. Slipcase already used a regular CDN and pre-processed its images; the low-hanging fruit was gone.
What FileJet does
FileJet is an asset proxy built by Everlution. It sits between the site and the visitor, inspects the headers each browser and device sends, and returns each image in the ideal format and size for that device — no more billboard-sized images sent to a phone. Assets are served from the closest of more than 240 edge locations to keep latency down. Integration is a URL change, not a redesign.
Before and after
Measured with Google’s audit tool (incognito) and the FileJet inspector, before on 9 April 2019 and after on 13 April 2019.
Home page
| Before | After | Change | |
|---|---|---|---|
| Performance | 46 | 91 | +45 |
| Accessibility | 67 | 94 | +27 |
| Best practices | 93 | 100 | +7 |
| SEO | 90 | 100 | +10 |
| Time to interactive | 16.3 s | 4.2 s | −12.1 s |
| Image weight (1600 px+ screens) | 2.41 MB | 0.7 MB | −1.71 MB |
Publications page — total weight 2.7 MB → 1.08 MB; image weight 1.81 MB → 0.38 MB; images as share of load 67% → 35%.
Article view — total weight 2.45 MB → 1.1 MB; image weight 1.54 MB → 0.40 MB; images as share of load 63% → 36%.
Some of the SEO score gain may come from minor changes shipped in the same release; the performance and weight numbers are the images.
Why it matters
The design did not change, the editorial team’s workflow did not change, and the site got four times faster to interact with. That is what “keep response times under control” looks like in practice.
A consultation with one of our engineers
Tell us what you are dealing with. Within two working days you get a concrete proposal with scope and price.
- Reply from a senior engineer or lead auditor, not an account manager
- Fixed scope and price before any work starts
- ISO 9001 and ISO 27001 certified processes, NDA on request