OneCAD/docs/perf.md

Viewport performance

Measured with the control channel (ui.inspect frame_ms: CPU time of one UI frame, which includes picking under the cursor) on the sample plate patterned 20 × 20 (400 bodies, about 600k triangles), 1600 × 1000 window under Xvfb, release build. Hover: 60 cursor moves across the model; orbit: a right-drag.

	hover median	hover p90	orbit median
before	18.7 ms	37.5 ms	21.0 ms
after	1.9 ms	2.4 ms	2.6 ms
after, Browser hidden	0.4 ms	—	0.4 ms

What changed:

• Picking culls by bounding box. Per-body boxes are cached until the model changes. The face raycast skips bodies whose box the ray misses or enters behind the nearest hit so far. Edge and vertex tests skip bodies whose box, projected on screen, is not under the cursor.
• Picks are reused while the cursor, camera and model are unchanged, and no picking runs while the view moves (orbit, pan, zoom).
• The model extent is cached (it sets the view's depth range and was recomputed from every mesh several times per frame).

With 49 bodies the frame was already 2.8 ms (hover) before these changes. The remaining frame time with the Browser shown is mostly the Browser listing every body row. GPU ID-buffer picking was not needed at this size.

Browser

Same model and method (400 bodies, Bodies folder open, 60 hover moves over the viewport):

	median	p90
Browser shown, before	1.95 ms	2.71 ms
Browser shown, after	0.72 ms	1.19 ms
Browser hidden	0.30 ms	0.72 ms

What changed: rows scrolled out of view only reserve their height. They register no widgets and paint nothing (no text layout, icons or eye/fold buttons), so the cost follows the rows on screen rather than the rows in the tree. Scrolling, Find in Browser and drag and drop still see every row's place.