Adds ui_selection_overlay bench (benches/performance_benchmarks.rs + README metric 31): builds a representative selection overlay element (snap, crosshair, UCS tripod, 128 grips quick / 4096 capped full) and times widget-tree construction. Measured 0.4us typical, 2.4us at the cap (threshold 50us).
Adds ribbon/statusbar section marks to the chrome bucket in view_main (src/app/view/mod.rs) so live PERF=1 view-detail traces attribute those two costs separately. Gated on the existing perf switch; no-op otherwise.
Adds pub re-exports of CursorType/IsoPlane (src/app/mod.rs) for the bench fixture (same pattern as the existing grip re-exports).
Ranked result over all ui_* benches: ribbon view construction ~556us (largest; follow-up already tracked), everything else under 50us or synthetic-fixture shapes. No new follow-up filed. GPU and canvas-draw costs are unmeasurable in headless runs (view() never executes there).
Placements (entity lookups, intersections, String labels, projections)
recomputed per view() and per mouse-move hit-test, with overlay re-clones
and 2-3x offset recomputes. New constraints_epoch bumped on every set
mutation/visibility/undo/DWG-load (plus new set_constraint_enabled API);
single-slot Arc<[GlyphEntry]> memo on an 11-field key (hover/selection
excluded); overlay de-cloned/de-duped to the single geometry source;
hit paths reuse the cache.
Tests:
- cached_glyph_placements_hit_returns_same_arc: same-key Arc identity
- cached_glyph_placements_invalidated_by_metadata_edit: edit + selection change yield new Arc
- glyph_hit_test_entries_matches_precomputed_boxes: shared hit-test helper
Bench (cargo bench glyph, 60 constraints): 8.18us -> 0.05-0.15us (~55x).
A/B reference deleted.
view_window() rebuilt the 256-bucket ACI layer-usage table inline on every
modal view: unconditional 256-Vec allocation plus sort_by_key (lowercase key
recomputed per comparison). Extract pure build_layer_usage(), build it only
when the CTB path needs it (STB path now allocates nothing), and sort with
sort_by_cached_key while skipping trivial buckets.
Tests:
- build_layer_usage_buckets_index_colors: ACI bucketing + case-insensitive order
- build_layer_usage_ignores_non_index_colors: truecolor layers excluded
Bench (cargo bench ui_plotstyle_layer_usage, 200 layers): ~13us median, PASS.
A/B vs pre-change inline code: ~15.7us -> ~12-13us (~22% faster).
Karim Jerbi