Fastly helps Speed Kit reduce LCP in high-traffic websites by 0.5 seconds — boosting conversion rates by 5-10%

When a customer lands on a website, time is money. So the Speed Kit plugin is an all-in-one page speed optimization tool helping leading brands like Decathlon and BMW minimize loading times to maximize profits. 

Speed Kit can be installed in Shopify, WordPress, and Plesk.

The brainchild of CEO Dr. Felix Gessert, the business evolved from a 2012 university doctoral thesis to a Backend-as-a-Service product (Baqend) in 2014, then to SaaS tool Speed Kit in 2017. 

Fastly is proud to have helped Speed Kit produce stunning results, amplifying performance, ramping up conversions, and banking significant egress cost savings. Plus, Speed Kit is using Fastly in innovative ways even we hadn’t envisioned.

The Challenge

Picking a platform — it takes one to know one

Felix considers Speed Kit to be a platform. In some ways, this fundamental utility informed its search for a partner to provide a powerful CDN and other simple, strong building pillars.

“We consider ourselves the building block you need to add into your website to take it to a level where end users won’t perceive loading time anymore. Our end goal is to get website loading times to around 100 milliseconds, which the current industry standard is still miles away from. Everything is centered on acceleration, but we recently broadened the scope to become an end-to-end performance platform, which includes observability and monitoring. Starting with ‘what does your performance look like?’, ‘what’s your real-time user monitoring data?’, and ‘what potential UX issues come from low speed?’, all the way up to implementing automatic acceleration.”

To provide Speed Kit’s SaaS to an enterprise audience, it initially needed a CDN that excelled in three areas: the flexibility to run complex computations on the edge, near-instant cache invalidations, and the ability to serve customers anywhere in the world through a centralized cloud location in Germany — without performance issues.

These criteria were crucial. Without a capable, worldwide caching infrastructure, Speed Kit can only accelerate through the browser, which is less effective as data isn’t shared across users. The choice was either picking a CDN highly customizable to its platform or building its own caching infrastructure. And happily, Baqend chose the former option in the shape of the Fastly CDN.

The solution

As Felix explains: “As we conducted research in caching, we knew the capabilities and reverse-proxy cache solutions of all major CDNs and always admired Fastly for its open communication, for example about the internals of the cache invalidation algorithm, which also offers instant purge. Fastly is probably the most enterprise-friendly CDN there is in the sense that every feature you deliver is well thought through and very well tested. When we think about the other CDNs, like Cloudflare and Akamai, we feel they’re much more like a bundle of features loosely tied together, while Fastly is very stable and scalable, with a combination of core features we’re very confident about using. The CDN, very flexible caching based on VCL and varnish, next-Gen WAF, and also parts on the edge platform we use — all of these form a great foundation for us to build upon.”

Fastly’s CDN fits well with Speed Kit’s existing stack and platform configuration too. The core pieces of infrastructure run on AWS in Frankfurt, with their analytics stack built on AWS and using several AWS services such as EC2, Amazon S3 for Storage, AWS Athena etc.

For each customer, Speed Kit runs several containerized application servers that Fastly distributes traffic to. Several systems serve the Speed Kit assets swiftly and consistently, and on a cache miss and updates like deployment, Speed Kit fetches resources directly from the customer’s origin and keeps the data stored in the Fastly cache and browser cache fresh.

With Fastly CDN deployed, it wasn’t long until Baqend explored ways the rest of Fastly’s platform could support Speed Kit’s medium to long-term vision. And now, Speed Kit uses Fastly for several purposes:

1. CDN: for the delivery of Speed Kit resources.


2. WAF: to make sure requests to the original servers are ‘clean’.


3. Compute: for advanced use cases around ‘compression dictionaries’ used for efficient predictive preloading of website content (more of which shortly).

Key takeaway

Speed Kit’s results with Fastly are impressive across the board, including a 98% Fastly cache hit rate for typical customers.

And Fastly Next-Gen WAF helps Speed Kit in a couple of important ways — firstly, it protects requests against origin from traditional attack vectors like SQL injections, so all such requests are pre-filtered by Next-Gen WAF and the traffic sent to the customer’s origin is clean. Secondly, a heavy reliance on performance data means it’s vital to understand which parts of the user base are bots, as this can skew metrics and measurability. A combination of Next-Gen WAF bot signals and Speed Kit’s own bottles means bots are easily flagged and with complete user journeys tracked, models are tuned to a false positive rate of zero.

And how about that all-important speed?

Check out the graph below, comparing the LCP results of a global automotive player before and after introducing Fastly-backed Speed Kit acceleration:

In terms of UX, Speed Kit can typically reduce LCP by 0.5 seconds with Fastly, greatly enhancing customer satisfaction.

And across various industries, Speed Kit has measured an improvement of 1-2% in conversion rates for every 100 milliseconds of improvement in the LCP.

Exciting figures. But what’s even more fascinating is Speed Kit is also leveraging Fastly CDN to create a kind of crystal ball for website visitors, called predictive preloading. When Speed Kit’s loaded on a customer website, it tracks all user interactions, knows all historic journeys and how users move their mouse or hover over links. Combining this client-side data with a machine learning model allows Speed Kit to predict where the user will navigate next.

On the flipside, there’s a heavy preloading process on certain sites — which in an online shop for instance, could amount to 50 pages. To alleviate this, Speed Kit is using Fastly Compute to create website-specific compression dictionaries which reduce the data volume down to 20% in size, saving 80% of bytes transferred over the network. Transforming old school, generic compression formats to customized compression dictionaries requires a lot of logic running on the edge, and it’s not possible in any kind of traditional request handling in VCL or on any of the other CDN platforms.

Speed Kit– the future with Fastly

So, what does the future hold for Baqend, Speed Kit and Fastly? Felix can’t consult his crystal ball for that answer, but feels positive nonetheless:

“We intend to stay with Fastly, that’s for sure. I guess the next question is whether we are going to switch completely to Compute for the rest of the projects we’re working on. And there are different parts of the product we’re using — for example, the new compliance routing is interesting because we have a lot of data-sensitive customers. But the one thing that goes really well with Fastly is we have very close contact with all the product teams. We can jump on a call and clarify if we can make our use case work, even for something we might build over the next few years. We value the opportunity to talk to the engineers directly and actually build things, not just have some account manager proxy our requests to someone else.”