When viewing large diffs in Bitbucket Server, using Chrome or Safari, and scrolling though the page, there is jitter. You will know you hit this state when you see the browser take a full CPU to render the screen. After the browser reaches the limits on one full core for your system, this is when the jitter happens. Firefox version 57 or better does not have this issue due to Stylo.
Bitbucket should have some basic logic to fall back to a static page if the amount of content is greater than X so that scrolling is actually usable. but to be honest i would also be okay with having a user preference to get static pages all the time. github and gitlab do this much more smartly — the pages themselves are static and then individual file diffs are collapsed by default if they are too large to display inline. a link allows you to then load that specific diff if you need it inline via ajax.