For a good while now I've been pretty happy with the PageSpeed measurements of this blog, which in turn means I've been happy with the state of what's generated by BlogMore. I have pretty much everything that can be minified nice and minimal. At this point, the main thing that causes the speed measurement to fluctuate is image sizes.

I use a lot of PNGs on this blog. When I'm using images, they're almost always in posts that include screenshots, which in turn pretty much demand that I use a lossless format. When I take these screenshots I don't worry too much about the dimensions (within reason), and of course I don't really do anything to optimise how they'll work and appear on different display sizes. If I was to get too into that, it would add friction to writing something, and the whole point of this is to feel less friction when it comes to sitting at the keyboard.

So I've been living with the fact that some images can be pretty big. While I do make a point of using pngcrush on every image, it generally doesn't make a huge saving.

Then yesterday I read this post on Andy's blog and I suddenly realised what I had to do!

I should use webp

Borrowing from what Andy did, I used mogrify too, setting up this Fish abbr in my Fish configuration:

if type -q mogrify
    abbr -g mkwebp "mogrify -format webp -define webp:lossless=true -quality 100"
end

In my case, at least in the initial experiment, I decided to keep it all lossless. So far the results have been really good, cutting the image sizes down by a significant amount. For example, if I look at the images for yesterday's posts:

 90581 15 Apr 18:14 sl-overview.png
 33446 16 Apr 20:23 sl-overview.webp
392661 15 Apr 18:14 slstats-region-info.png
225392 16 Apr 20:23 slstats-region-info.webp
 36049 15 Apr 19:39 year-chart.png
 15590 16 Apr 20:23 year-chart.webp

That's a pretty reasonable saving!

So far all I've done is convert the few latest posts that make up the front page of my blog, just so I can see what impact it has. I'm getting improved load times on mobile, for sure.

There are a couple of downsides to this, of course.

  1. Now I want to do the whole blog, so while I can easily go through and convert all the png files to webp, converting all the image markup in the Markdown files isn't quite so simple, and even if I do write something to automate it, I'm then going to want to review it to make 100% sure nothing has broken.
  2. I can't just then remove all the png files to cut back on the space used by the generated site. The front page of the site has a feed, and all the categories have a feed each too. This means that there could be HTML out there from some of my oldest posts, referring to the png files, and just removing them will result in broken images.

Overall though, it might be worth doing at some point soon. Meanwhile, from now on, I think I'm going to replace my pngcrush step with a mkwebp step and just use webp instead of png now.

I guess I'm all modern now!