I never usually think about the speed of any site I work on or visit. Until this weekend when I had no internet. The 4G/3G on my phone was sometimes as fast as WiFi (generally early in the morning/late at night) but sometimes was so slow nothing would load at all.
Often it was somewhere in between. Which meant if you waited a few minutes and didn't want to see images, and the site was simple, then you could read it. It was like being back on dial-up: in those days we turned the images off in the browser because they made sites too slow.
The most frustrating site/app was the Wimbledon one. If I wanted to know the live scores I could listen to the radio and wait until they recapped any of them. Or put Wimbledon into a Google search. The site and app just refused to load.
They have a lot going on with their live scores. There are potentially 19 courts with matches going on and they give you the exact point score, updated when the scoreboards on the court are updated (I assume, I don't know what the lag is there, but if you watch the tennis on the iPlayer then the live scores are ahead). And for each match you can open up a sidebar that tells you what's going on for each point. (It also tells you whether the momentum is with the green player or the purple player, although doesn't tell you which player is assigned to which colour).
I get that that's a lot to load. But I'd happily have had a static version that only refreshed when I loaded the page and didn't look as good.