The scrolling on worldbuilding.SE and its meta is very unpleasant on macOS Safari. It's like it's running at low fps.
For over 2 years we still have this bug in macOS Safari where worldbuilding.SE (and no other site) has awful, choppy, laggy scrolling.
it runs at a very choppy pace ... Scrolling on any page feels laggy and choppy to the extent that the site becomes hard to use
choppy, laggy scrolling. It's very unpleasant to use
When scrolling down or up there is a noticeable frame-rate drop. What is intended to be smooth ends up been jerky
We poor Safari users have all managed to "fix" the issue through inspect element and disabling the
background-attachment style rule on body. Unfortunately that causes the robot to not stick to its place in the bottom-left of the screen after scrolling down.
And also, perhaps like this question and this question where the askers were using Microsoft Edge, the background flickers and jumps around sometimes while scrolling. This is especially noticeable while scrolling fast or before the page has entirely loaded all content (like images).
Maybe like edge Safari has a bug of its own that causes this behaviour. Why not float the robot as its own element instead of as a page background?