That's a bit odd, what browser is this? The fixed background should be handled by compositor layers, and while it is certainly more expensive than having a scrolling background, I'm surprised it makes the experience unusable.

Courtesy of https://fourword.fourkitchens.com/article/fix-scrolling-perf... , remove the fixed background and instead place it in its own layer with will-chance: transform.

  .wrapper::before {
    content: ' ';
    position: fixed;
    height: 100%;
    width: 100%;
    top: 0;
    left: 0;
    background: url('data:image/png;base64,...');
    will-change: transform;
  }

Tested with Chrome dev tools, the repaint troubles disappear. Unfortunately only supported in Chrome, Firefox, and Opera. But just checked, and at least in Chrome the performance problem goes away with this solution even with the will-change removed. YMMV

I get the lag too. MBP 15" Late 2014.

There's also this script:

http://htty.github.io/htty/javascripts/scale.fix.js

which appears to add a 'gesturestart' event, and a weird conditional comment at the bottom that shouldn't appear for non-IE, but whose condition is to explicitly run the function defined in that script in non-IE browsers...

Definitely lagging here, brand new 12" macbook running chrome.