This is because when this configuration is true, Firefox gives Vimium fake timestamps (something like 0, 0, 0.1sec, 0.1sec, 0.1sec, 0.2sec, 0.2sec, 0.3sec, ...), and Vimium fails in computing scrolling distance if a second timestamp is equal with the one before.

When this is false, then the timestamp will be like 0, 0.017sec, 0.034sec, 0.051sec, ... - the precision is much higher.

Are there any solutions to this? I can confirm that window.scrollBy works around the issue with timing:

window.scrollBy({
          top: 100,
          left: 0,
          behavior: 'smooth'
        });

Vimium can work with behavior: 'smooth' - only when the "Use smooth scrolling" is disabled and you don't hold on the key of scroll commands.

How do I implement this? I toggled off "Use smooth scrolling" and I am running v1.66.

Update:
I changed this line and re-built. Holding the scroll keys works fine.