Performance

Measure	Result
Desktop, 166 structures, integrated GPU	display refresh rate (144 Hz)

The 3D view draws every structure with one composite object and picks with the GPU, so it scales to thousands of structures; it switches to a lighter level of detail when the scene exceeds 3 million triangles. Budgets enforced by pytest -m perf: opening a 5,000-structure atlas under 200 ms, search under 10 ms per keystroke, a slice under 5 ms. With the real atlas built, pytest -m slow checks start to first frame under 2 s, the app's own memory under 400 MB (shared libraries such as Qt and VTK not counted, since how much of them is resident depends on what the system has cached), selection under 7 ms, a generated 3,500-structure scene at 60 fps or more, and quiz timing: a quiz starts under 100 ms, moves to the next question under 50 ms and checks a typed answer under 1 ms. Tracts are built the first time they are shown (under 500 ms), then show or hide in under 50 ms; a slice with every tract outlined redraws in under 10 ms. Entering a pathway or switching its side takes under 100 ms, a step under 30 ms, and a playing timeline updates in under 5 ms per tick.