forced synchronous layout

RU: форсированная синхронная компоновка

A browser performance problem where JavaScript reads a layout property (e.g. offsetWidth, getBoundingClientRect) after writing to the DOM in the same frame, forcing the browser to flush pending style and layout work synchronously before returning the value. A single forced reflow can cost tens of milliseconds; reading then writing in a loop (layout thrashing) can push INP into poor territory.