The per-element .accessibilitySortPriority read slots.count from inside the ForEach closure, re-running the whole slots -> renderedCards chain (an O(n) card filter plus the session's hidden-member resolution) once per element -- O(n^2) per lane body. A drag pickup runs a synchronous whole-board layout inside the drag-start nested run loop, which multiplied this into a stack- sampled ~700ms-1s stall between mouse-down and the visible lift. Hoisting the evaluation into a local makes pickup effectively immediate. Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY