@LukasEriksen This works when inserted into Settings->Advanced->Code Injection:
You can test by scrolling with your up/down arrow keys and see how it's smooth vs choppy without it.
<script src="https://code.nath.co/src/jQuery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/smoothscroll/1.4.10/SmoothScroll.min.js"></script>
<script>SmoothScroll({
// Scrolling Core
animationTime : 2000, // [ms]
stepSize : 100, // [px]
// Acceleration
accelerationDelta : 50, // 50
accelerationMax : 3, // 3
// Keyboard Settings
keyboardSupport : true, // option
arrowScroll : 50, // [px]
// Pulse (less tweakable)
// ratio of "tail" to "acceleration"
pulseAlgorithm : true,
pulseScale : 4,
pulseNormalize : 1,
// Other
touchpadSupport : false, // ignore touchpad by default
fixedBackground : true,
excluded : ''
})</script>