Thanks everyone for taking the time to look into it and reply.
[quote=437433:@Alberto De Poo]Can you share the Xojo code?
I tried to reproduce the behavior with that URL and HTMLViewer, but for me I can’t see any difference. Tested on Xojo 2019r1 and 2018r3, 2 different Macbook Pro, macOS 10.12.6. Let me try on Mojave with a remote debug.
Edit: tried on Macbook Air with Mojave 10.14.3 then updated to 10.14.5 and I don’t see any jerkiness.[/quote]
There is nothing special in the code, it is simply something like: htmlviewer.LoadURL(url)
If you are not seeing it on testing, on the one hand it’s annoying that the problem is not consistently reproducible and makes it harder to identify the cause, on the other hand, hopefully it means most of my users won’t have this issue.
Granted you have what appears to be quite a large amount of content on this page and some of those images could be optimized by having them downsized in advance of the page load (to potentially fixed HTML/CSS dimensions), so the HTMLViewer doesn’t have to do the resizing work dynamically…
I hope that helps.
PS. Nice work on the site, by the way.[/quote]
Thanks for your kind words I worked my way through all the tutorials on w3schools.com and that is the end result.
I tried changing the CSS so that all images are displayed at a fixed width, 600px (was previously set to 70%). Unfortunately that didn’t seem to make a difference. However, I did notice that if I make the htmlviewer size smaller - and image widths set to 70% - so that the images are smaller, then the jerkiness is much less noticeable. So I’m sure you are on the right track and it has to do with what behind the scenes work the browser has to do to render the images.
Well, somewhere in the Xojo User Guide there is a quote saying something like “trying to optimise too early is the enemy of productivity”. I have much bigger things to sort out to get my project fully functional, so I might park this issue for the time being
Thanks again for the input, it is much appreciated.