SLIM

SLIM (Scalable Lightweight Interactive Models) is an automatic optimization system that generates lightweight, optimized representations of Models and platform avatars using cloud-based transcoding (converting assets into more efficient formats). When enabled, SLIM combines multiple parts into fewer draw calls (rendering commands sent to the GPU) and generates multiple levels of detail, allowing the engine to intelligently select the best representation based on distance, device capability, and available resources.

SLIM provides three key benefits:

• Visual Quality

  — Distant models appear more detailed than the legacy model level‑of‑detail system, maintaining closer fidelity to the original.
• Consistent Transitions

  — All parts within a model switch detail levels simultaneously, eliminating jarring per-part transitions.
• Performance

  — Composite meshes dramatically reduce draw calls, triangle counts, and memory usage, enabling richer scenes across all device tiers.

Explore SLIM in these published games:

Prerequisites

SLIM requires the following:

1. StreamingEnabled must be enabled on the Workspace object. See also streaming properties for related recommended settings.
2. The place must be saved to Roblox (not a local .rbxl file), as SLIM uses cloud transcoding to generate optimized assets. If you're testing locally, publish the place and then enable SLIM.
3. Team Create must be enabled for the game, as SLIM relies on associated properties for cloud asset generation.

Technical behavior

When you publish or playtest a game with SLIM-enabled models, the engine uploads model data to a cloud service that generates optimized composite meshes with multiple levels of detail. At runtime, clients fetch these assets from the CDN and the engine selects the appropriate detail level based on distance and device capability, classifying each SLIM model into rendering zones based on distance from the camera:

SLIM for models

SLIM works best on models that represent static world geometry — buildings, props, vehicles, terrain features, and other environment objects that don't change at/during runtime. Adding or removing parts, changing materials, or modifying geometry at runtime prevents SLIM from rendering the model correctly. See model structure for general model structure guidance and limitations for the full list of exclusions.

To enable SLIM on a model, set its LevelOfDetail property to SLIM in the Properties window.

When SLIM is set on a model, the engine:

1. Serializes the model's rendering-relevant properties (geometry, materials, textures, transforms) into a compact representation. Supported instance types within the model include Part, MeshPart, Decal, Texture, SurfaceAppearance, PartOperation, NegateOperation, and SpecialMesh.
2. Uploads this data to the cloud transcoding service on first publish or play.
3. The cloud service generates a composited mesh with multiple levels of detail, removing hidden internal geometry and optimizing textures.
4. At runtime, clients fetch the optimized SLIM asset and render it when the engine streams out the original model or when SLIM is more efficient than the full model.

Batch-Convert StreamingMesh to SLIM
for _, descendant in workspace:GetDescendants() do
    if descendant:IsA("Model") and descendant.LevelOfDetail ==
        Enum.ModelLevelOfDetail.StreamingMesh then
        descendant.LevelOfDetail = Enum.ModelLevelOfDetail.SLIM
    end
end

SLIM for avatars

Platform avatars outside of the currently streamed area are not visible by default. Enabling SLIM avatars renders standard‑rig player characters — regardless of how many accessories or clothing layers they have — as lightweight, animated stand‑ins that maintain visual fidelity at a fraction of the rendering cost.

SLIM Enabled

~170,000 triangles

~4,000 client instances

SLIM Disabled

~2,600,000 triangles

~60,000 client instances

The key SLIM-specific property for avatars is Workspace.EnableSLIMAvatars which should be set to Enabled in the Properties window, alongside LevelOfDetail set to SLIM on your non‑avatar world models.

With EnableSLIMAvatars enabled, the engine:

• Renders a SLIM version when an actual avatar model streams out.
• Swaps between SLIM and full-resolution representations based on available resources, even inside the streaming radius.
• Throttles SLIM animations based on scene importance and available bandwidth.

Limitations

Troubleshooting