Fix: Unity Tilemap Collision Shape Update Too Slow on Large Maps

Procedural generation runs CompositeCollider2D.GenerateGeometry per tile change. Frame freezes during gen.

Update chunks only

For large maps, split into 16x16 sub-tilemaps. Modify only the affected sub-tilemap; rebuild collision only there.

Or pre-bake

Offline tools that bake collision once; load at runtime. Avoids runtime cost entirely.

Use Optimization parameter

CompositeCollider2D > Optimization > Don't Trim. Skips the trim pass that's a significant share of the cost.

“Composite collider regen is O(n). Large maps hit the linearity.”

For procedural worlds, chunked architecture is non-optional. The pattern affects every system, not just collision.

Related reading

• Fix: Unity Procedural Mesh Recalculate Normals Too Slow
• Fix: Unity Skinned Mesh Blend Shape Weight Not Replicating
• Fix: Unity Physics Character Controller Uphill Slow
• Fix: Unity Mesh Collider Cooking Options Slow Load