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Performance and VRAM

Identify which part of the setup is expensive before reducing quality. Grid resolution, particle count, solver work, preview and generated geometry have different costs.

DENSE 3D GRIDS Half the voxel size means roughly 8x as many cells

For the same fixed three-dimensional domain, halving cell size doubles resolution on each axis. That creates about eight times as many cells in a dense grid. Sparse grids also become more expensive at higher resolution, but their cost depends on the active region.

Keep resolution controls separate

SIMULATIONGrid resolution

How finely a solver resolves a domain or field.

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PARTICLESParticle spacing

How densely particles sample or represent a material.

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DISPLAYPreview or render size

How simulated data is drawn or converted into output geometry.

Find and reduce the slowdown

  1. Reproduce the slowdown with the smallest scene that still shows it.
  2. Determine whether the dominant cost is a grid, particle count, solver feature, viewport path or generated geometry.
  3. Change only the control responsible for that cost.
  4. Keep simulation resolution and display quality independent where possible.
  5. Recheck VRAM after adding secondary systems such as Flow Fields, Pyro, whitewater, deformables or Mesher layers.

Grid-based systems

FLIP, MPM, Flow Field and Pyro use voxel grids. Smaller voxels resolve smaller features but increase cell count and memory use. For a fixed dense 3D domain, the cost rises cubically with linear resolution.

Sparse Pyro stores active regions instead of the entire dense domain. Higher resolution still increases cost, and moving or expanding smoke may activate more sparse cells. Leave enough sparse capacity for the expected motion, especially when moving deformables activate cells outside the initially visible smoke.

Particle count

Particle cost grows with emitted particles and with neighborhood work performed by effects such as self interaction, granular materials, particle constraints and particle-scale fluids. One-time volume fills can create many particles at once. With FLIP pre-fill, smaller pre-fill particles create a denser initial liquid and may increase memory use substantially.

Preview and geometry

GPU Preview is suitable for interactive work. Use Blender Geometry when you need Blender modifiers, geometry inspection, Output Cache or renderable geometry. At high particle counts, creating Blender Geometry can take more time and memory than the simulation itself.

Mesher resolution, Trails history, Instance source complexity and deformable visible-mesh resolution affect output cost independently of the underlying simulation.

Pyro VRAM guidance

A dedicated GPU is strongly recommended. The installation requirements use 6 GB VRAM as a practical minimum for Pyro, with 8 GB or more recommended for larger scenes. Actual capacity depends on voxel size, domain size, active sparse cells, enabled channels, preview mode and other GPU workloads in Blender.

Terrain preview and export

Terrain uses a two-dimensional heightfield. Doubling resolution on both axes quadruples its sample count. More complex graphs and connected color or mask fields increase memory use further.

  • Lower Preview Resolution while arranging a graph, then inspect fine detail at 2K or 4K. GPU Preview displays the native field; Heightfield Geometry uses a bounded mesh.
  • Node Cache (MB) limits reusable preview results in RAM, not GPU memory. It can speed up repeated edits but does not cover all working memory. See Preview Cache.
  • Each export node has its own Resolution. Lowering Preview Resolution does not lower export resolution or export memory use.
  • Grid Reduction reduces exported mesh density, not upstream graph resolution or image resolution. A dense mesh can also consume substantial RAM when imported into Blender.
  • 8K and 16K exports can require substantially more RAM and calculation time than previews. GPU memory use also depends on the graph and connected maps.

See Native resolution and memory for memory guidance and output sizes, and Terrain Troubleshooting for slow editing.

When a scene runs out of memory

Start with the part of the scene using the most memory. Typical checks are:

  • increase voxel size for the grid that dominates memory
  • reduce domain bounds where possible
  • lower particle density or one-time fill density
  • reduce whitewater or secondary-particle budgets
  • reduce Pyro sparse capacity if it is significantly above the active requirement, or increase it only when the simulation genuinely exhausts the current capacity
  • simplify generated geometry or use GPU Preview while iterating
  • disable channels, mappings or secondary systems that are not needed for the shot