Hi! Being able to scroll through messages quickly has been a core design goal for the Zulip web application from the beginning, and we're not aware of any significant regressions here, so I'd like to get to the bottom of it.
I'd love it if you reported what you're experiencing in #frontend in chat.zulip.org. We'll want to collect a profile from your browser, so we can figure out why you're seeing choppy scrolling.