Key Facts

• Google reduced scroll jank in Chrome for Android by 48% between 2023 and 2026, as detailed in a report on the company's efforts to improve the mobile web experience.
• Scroll jank refers to sudden page stutters or jumps that occur when a device fails to present a frame containing an updated scroll offset on time, typically resulting in a jarring, jerky stutter perceived by the human eye.
• Chrome's multi-process pipeline, which includes separate browser, renderer, and GPU processes, can exacerbate scroll jank due to the complex path input events and VSync signals take across multiple processes.
• To address this issue, Google worked with Android to prioritize input threads, ensuring that all threads responsible for delivering hardware input to Chrome have a sufficiently high priority to prevent preemption by lower-priority work.
• The improvement in scroll jank reduction was achieved through a combination of automated heuristics, targeted optimizations, and deep architectural shifts in Chrome's input-to-frame delivery process, which aimed to provide consistent frame delivery before screen refreshes.