> [!abstract] Summary > **Solaris / USD performance tips** — keep the prim count low (consolidate meshes, use GeomSubsets for materials instead of splitting prims), group everything under a single root prim (`/world` or `/Scene`), use Payloads for heavy data, and avoid SOP Modify on the hot path. High sibling counts hurt USD and Hydra noticeably. --- # Core Rules - **Consolidate meshes** — high numbers of [primitives](https://www.sidefx.com/docs/houdini/solaris/glossary.html#prims) can slow down USD and Hydra, particularly when you have **hundreds or thousands of sibling primitives**. - Use **GeomSubsets** to bind materials to different parts of a single mesh instead of splitting prims. See [[../SCENE GRAPH/SOLARIS GEOMsubset|SOLARIS GEOMsubset]]. - **Group prims under a single root** — essential when building assets (so referencing works), and recommended for scenes. Common roots: `/Scene`, `/world`. --- # Additional Tips - **Use Payloads for heavy assets** ([[../NODES/Houdini Payload|Houdini Payload]]) — defer loading until needed. - **Use Instancers / Point Instancers** for repeating geometry ([[../WORKFLOW/SOLARIS Instancing|SOLARIS Instancing]]). - **Avoid SOP Modify on the hot path** — it forces full geometry evaluation. Use LOP-native nodes ([[../NODES/SOLARIS Mesh Edit|Mesh Edit]], [[../NODES/SOLARIS Geometry settings|Geometry Settings]]) when possible. - **Clean attributes before USD export** — see [[../6.125 HOUDINI USD Attribute|HOUDINI USD Attribute]]. - **Mip-map your textures** — see [[../../KARMA/Notes/KARMA MIPMAP|KARMA MIPMAP]]. - **Layer Break** ([[../NODES/SOLARIS Layerbreak|SOLARIS Layerbreak]]) — only the right slice of the network ends up on disk. --- # 🔗 Related - [[../SOLARIS MOC|SOLARIS MOC]]. - [[SOLARIS Fix and problems|Fix and Problems]] — specific bug workarounds. - [[../../../../PROTOCOL/OPTIMISATION/OPTIMISATION MOC|OPTIMISATION MOC]] — pipeline-level perf guidance. - [[../../../../PROTOCOL/USD/Notes/USD Practice/USD Maximizing Performance - by pixar|USD Maximizing Performance — by Pixar]]. - [[../../../../PROTOCOL/USD/Notes/USD Practice/USD Jemalloc use|USD Jemalloc Use]] — memory allocator.