Demo Love? Demo Live!

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CGNwebperf Meetup Cologne, Germany

The 18th #CGNwebperf Meetup took place at the Choi&Lager Gallery in Cologne, Germany. #CGNwebperf is a series of meetups around the topic of web performance and mostly its technical aspects.

Stefan Böck, the organizer, invited me following our silent launch at the dmexco ‘17 to demo to a technical audience.

As a huge fan of the meetup culture, I was very pleased to be invited as a speaker.

However, publically speaking in front of a larger audience that has very specific questions in regards to every presentation was frightening.
My own expectations of a presentation are quite high, since presentation and topic should match and be interestingly presented.

Reviewing the idea of a live demo with our internal team helped me to overcome my hesitations – so it was decided – my first meetup as a speaker.

Sticking to the concept of demoing live, I added introductory information to get everyone on the same level. The last rehearsal in front of my colleagues at the forenoon of the presentation and go!

Live Demo


At the gallery, I was already expected by Sebastian Thielen, the mastermind behind the Analyzer, Stefan Böck and Alexander Thurn, the second speaker.

Alexander Thurn presenting his UFP Optimizer

After a short visit to the arty location, we quickly organized some food and drinks to ensure a convivial get together.

Welcoming the first participants on time (7 pm) and getting to know each other over Pizza and Beer – my stage fright became less.

Art, tasty Pizza and Web Performance. What a dream!

Starting with an interactive Question & Answer round and was surprised how well the audience knew the e.g. the page weight of their own websites. Down to the kilobyte (kb), more than three people knew the size of their website!

Having planned the “what is your website´s size” question as a transition into the live demo part, I started with the Analyzer to check with the audience the size of their websites and the possible optimization through

The demo gods were gracious so that I could explain the workflow, the features and the technology behind on the basis of

Starting with the Analyzer to check what kind of speed improvements I would gain and (!) to get automatically the appropriate setup for a demo URL – (not in use, since the site is live on

Toggling the different features manually to demo the variety of performance improvements we discovered together the full potential of
How does “image delaying with blurry placeholders” look on my demo site? Is the CSS still working as it should, when “CSS minifying” is activated? Does the site fully render, when “inlining” is activated?
Yes, every single toggled feature worked.


The site was optimized to its maximum potential. Time for the next step!

Live Demo – GO live!

Before actually really going live with a handful of questions aroused. The demo domain was challenged.

Is it really possible to test the optimizations of a website before actually implementing the software?
Yes, it is! With tools like the Chrome Developer Tools or (for the security features) the differences were clearly visible.
An excited murmur went through the audience.

The next questioner wanted to know, why the automatic setup over the Analyzer did not switch on all available features?
As shortly explained, the automatic demo domain setup tries to find the most relevant settings. This means the features that definitely enhance the performance or security are activated.
Letting the user still the manual control of activating or deactivating certain features was highly appreciated by the audience.

However, the goal was to show that not only the demo domain worked but that it´s really easy to go live with the optimization of an existing website.

Two steps!

First, I switched off the demo mode in my account. A small error notice appeared – “Let´s encrypt certificate could not be obtained”.

Did I break something? Did the demo gods leave?

No, this was to show that provides a free SSL certificate from Let´s Encrypt for any user of and to prepare the second step.

Second step, changing the A-Record at my hoster, in this case, 1&1. Entering the needed IP, clicking save and presenting a fully optimized website – done!

Question & Answers

The following discussion opened up and a lot of questions about the different features like “Webfont Compression” and especially the image compression algorithm.
With our own image compression algorithm, the highest speed improvements were visible at the demo site and at the audiences sites. This clearly sparked the interest and a discussion developed.

However, to explain the algorithm in detail, an own blog post is needed.

Coming to an end I would like to point out that the audience’s feedback touched me, as for example, Michael Schilling wrote: “Both presentations were really informative and to the point. It was easy to follow and absolutely great to dive into the discussions. Looking forward to the next meetup!”

And in addition I learned about a new image format, that is supposed to be even more performant than WebP, Flif.

Thanks to #CGNwebperf for the invitation – a real diamond in the Cologne meetup scene.

By the way: You would like to optimize your website? Join us on!

Speaker & Author: Heinrich Rauh | Photo by Paul Weiss

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