Chrome/Lighthouse Performance Testing

[Sheri Steeves]

Hello,

We've been working at improving the responsiveness of our userguide pages on our website and running Chrome's Lighthouse to evaluate.

It has reported some things that it says would improve them, such as using next get image formats (WebP, AVIF) and having an explicit width and height on the images, among others. I can only choose between PNG and JPG for the images - any plans for supporting the new formats?

The current site uses a V3 skin from Premium Pack 4, I've updated to that skin for PP4.4 but not pushed it live yet, Do the new skins offer any improvement? Would migrating to a V4 responsive skin offer any advantages?

Thanks

Sheri

[Tim Green]

Hi Sheri,

Running these kinds of analyses is often a little misleading, and they will make blanket suggestions that may just result in a lot of extra work that might provide measurable improvements that would be impossible to notice subjectively.

It has reported some things that it says would improve them, such as using next get image formats (WebP, AVIF)

Well, yes, they do provide better compression and slightly improved quality under some circumstances. But like 5G versus 4G, the "benefits" are not nearly as great in the real world as touted theoretically, and some users would still be using browsers that wouldn't know what to do with them.

Help+Manual does already support WebP images, but they are so little used that they are still pretty irrelevant. They are a replacement for PNG for screenshot type images, with slightly better compression, and they also support transparency, just like PNG. Also, some people with older browsers won't be able to see them, so I wouldn't really recommend them anyway. We don't support AVIF because it's irrelevant for screenshots -- it would only provide benefits for photos, not for screenshots, and browser support is more limited than WebP. Bottom line: For documentation both formats are still not really relevant.

and having an explicit width and height on the images, among others. I can only choose between PNG and JPG for the images - any plans for supporting the new formats?

We are certainly looking into providing support for them if they become popular enough. For the time being you will still be fine if you use JPG for photos and PNG or GIF for screenshots. If you can get away with GIFs (they support a limited number of colors compared to PNG) your files will be a lot smaller than PNGs.

The suggestion to use images with fixed dimensions is actually counterproductive and really bad advice: Yes, it might provide a very slight speed improvement (also unlikely to be subjectively noticeable in most cases), but it would also break your layout on mobile devices. Setting your image dimensions to % of page width is essential for responsive web page performance on different screen resolutions and device types.

The current site uses a V3 skin from Premium Pack 4, I've updated to that skin for PP4.4 but not pushed it live yet, Do the new skins offer any improvement? Would migrating to a V4 responsive skin offer any advantages?

Not necessarily in terms of speed. The entire WebHelp 3 format used in the V3 and V4 skins is already lightning fast compared to any other web technology. The kind of analysis tool you are using will only measure the loading of the initial page, which must be a normal HTML page. It won't take into consideration the massive speed improvement you get for browsing within the help once the WebHelp has loaded. Loading a new topic in V4 and V3 generally only takes between 50 and 300 milliseconds (thousandths of a second), compared to up to a couple of seconds for a regular HTML page.