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Anton Caceres: Performance Is Not Milliseconds

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Talk by Anton Caceres at the Plone Conference 2019 in Ferrara.

You can measure the performance of your website in the milliseconds it takes to handle a request, or how many requests per second. But this talk is about subjective speed: how fast does it feel? The contents of the page come to us at the speed of light. But it has to show up on the screen, and then your brain needs to process it.

And when you do an online payment, it may be irritating when it is slow, but even worse when you just end up on a homepage without indication of success or failure.

Perceived performance is dependent on the actual performance, the UX (user experience), and the expectec performance.

If your brain is active, time seems to move faster. If a page takes less than a second to load, do you really need a spinner or progress bar? The Polar app at some point changed to show a spinner for every action. Nothing changed in the speed, but reviews dropped: it reminded you that you had to wait all the time.

So instead, you may be able to distract the user. The user needs time to focus. So don't show a blank page, but show a skeleton page, which has roughly the structure of the page. Then the user already has a chance to see where the focus should be. I hope Plone will do this.

Show a spinner for ten seconds: slow. Show a simple animation for ten seconds: you don't notice that it is just as slow.

The perception of performance is often just as important as actual performance.