I just want to note how fast this page is. 806kB transferred. 766ms to finished. I hit the DFW AWS CloudFront pop from here. Similar page for BK https://www.burgerking.co.jp/menu 31MB transferred. 6.5s to finished. Hits the DEN pop (but it's a "miss"). I am in Colorado. uBlock is on. Even if you don't count the 7.5MB of fonts on the BK page, that's wild.
McDonalds actually seems to have learned to take latency seriously. When their touch screen ordering systems were first deployed, the delay between tapping on an item or button was quite noticeable. These days the systems respond nearly instantaneously. I'm very glad there are people inside such a large organization that pay attention to that aspect of usability. Now if only every other website on the internet would…
When they first came out, everything was snappy because it wasn't loading recommendations or additional tracking. There were a lot fewer customization options.
Now, you click on something, and you wait a while, and then it asks you what you want to change and if you want to add these other suggested items. When you want to check out, it lags and then pops up another dialog asking if you want to add more items to your order.