Every time the user scrolls, this site updates a style attribute on the root <html> element with this a CSS variable: --scrolltop:700 (that appears to be first updating to the actual scrollTop value, THEN re-updating the value rounded to 100 increments). So TWO updates to this variable every scroll event.

There's a media query consuming this variable, and doing a calculation:

--logo-y: calc(3em - var(--scrolltop, 0) * 1px);

So every time the user scrolls, TWO variable updates take place, TWO redraws, and TWO of these calculations take place, TWO more redraws, just to center the sunburst background on the logo.