- Split M2 instances into fast-path index lists (animated, particle-only,
particle-all, smoke) to avoid iterating all 46K instances per frame
- Cache model flags (hasAnimation, disableAnimation, isSmoke, etc.) on
M2Instance struct to eliminate per-frame hash lookups
- Replace full rebuildSpatialIndex on position/transform updates with
incremental grid cell remove+add, preventing 8.5ms/frame rebuild cost
- Advance animTime for all instances (texture UV animation) but only
compute bones and particles for the ~3K that need it
M2_UPDATE: 10.7ms → 2.0ms, FPS: 35 → 55-59
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