The chat pane decides re-windowing once per frame from scrollTop and cached row heights instead of reading layout per scroll event. Rendered Markdown hast trees are cached, so remounted rows skip parsing. Sidebar lists of 60+ conversations mount only rows near the viewport. The perf driver scrolls the windowed sidebar to reach a row.
Also includes pending workspace changes: unsaved-change guard, keep-alive cache and live message store, knowledge workspace dialogs and perf driver updates.
perf:app gains GB_PERF_CPU_THROTTLE (CDP renderer throttling) and a keep-alive memory scenario with post-GC heap samples; perf:knowledge times synchronous FTS, vector and hybrid search at 5k/20k/50k chunks. Results and conclusions recorded in the performance plan (PERF-05, PERF-09, PERF-12).