LOD Optimization: Fix Pop, Cut Draw Calls, Boost FPS

We encounter LOD issues on every second project. A misconfigured LOD Group in Unity does the opposite of what's intended: LOD0 switches to LOD1 too early, the player sees a sharp pop, and it feels like a bug. Or transitions are set by Screen Relative Height without accounting for actual distance—on orthographic cameras, LOD simply doesn't work. Our goal is to make LOD invisible yet effective.

The essence is that LOD is a system for managing scene complexity based on object visibility. It works correctly only when we account for: camera type, player movement speed, lighting (shadow casting from LOD1 is often worse than LOD0), and how the engine calculates distance.

How LOD pop arises and what to do about it

LOD pop is the main visual problem. It happens when the geometry and/or textures between levels differ too much. Classic case: an artist created LOD1 with 60% fewer polygons, but the UV layout shifted, and the normal map doesn't compensate for the loss of shape. The transition at 10 meters is visible to the naked eye. The fix is proper LOD generation (we use Simplygon or the Unity LOD Generator) while preserving UV seams and checking normal projection.

Shadows don't follow LOD transitions. In Unity, Shadow Caster Culling works independently of LOD Group. If you have LOD2 as a flat billboard with 2 polygons, but the shadow is still computed from the LOD0 mesh (because Force Shadow Casting = On), you pay for rendering shadows from the full geometry of an object that's visually absent. It's easy to miss—Frame Debugger shows a Shadow Pass with full draw call budget. We guarantee elimination of such hidden costs.

HLOD (Hierarchical LOD) not configured for large scenes. In open-world projects, standard LOD Group fails beyond 500 meters—objects are culled but the scene isn't unloaded. Unity HLOD (via the HLOD Creator package) automatically merges distant objects into a single mesh. Without it, you may have 3000 draw calls from trees on the horizon. We'll assess your project in 1–2 days.

Why LOD policy must differ per object type

We set a separate LOD policy for each category (characters, buildings, props, vegetation). Example from a mobile RPG with a 2×2 km open world: Trees: LOD0 (500 polygons) up to 15m, LOD1 (80 polygons) up to 50m, LOD2 (billboard cross) up to 150m, Culled beyond 150m. Buildings: LOD0 up to 30m, LOD1 up to 80m, LOD2 up to 200m. This configuration reduced draw calls from 680 to 210 in the city center.

For Unreal Engine, we use Nanite where applicable—on static meshes with high poly count. But Nanite doesn't replace LOD for moving objects and doesn't work with translucent materials. We configure HLOD in UE5 via World Partition HLOD Layer. According to the Unreal Engine documentation, Nanite best practice requires disabling LOD for Nanite meshes.

Cross-fading instead of hard pop. Unity LOD Group supports Cross Fade mode—a dithering transition between levels. It works via the Dither Fade shader keyword. On mobile, dithering is cheaper than you think—Adreno parallelizes it well. We enable it for large foreground objects, and keep instant transition for small faraway props.

Vegetation is a separate story. SpeedTree LOD integrates into Unity through a separate pipeline. The main pitfall: SpeedTree billboard LOD is rendered via a separate BatchRendererGroup, and you must profile it separately from the main draw call counter. We've seen projects where 40% of GPU time went to 2000 billboard trees that seemed "already optimized." We train teams on such nuances as part of support.

How to set up LOD in 5 steps

1. GPU profiling: Open Profiler → GPU Usage and Frame Debugger filtered by draw calls. Identify how many objects are rendered with excessive detail.
2. Overdraw analysis: In Scene View, enable Overdraw mode—find objects with high overdraw without LOD.
3. Classification: Divide objects into categories and set level counts and threshold distances per the table below.
4. LOD generation: Use Simplygon or the built-in generator. For critical meshes, manual refinement.
5. Testing on target platform: Check for pop absence and FPS improvement.

Our process for LOD work

The audit starts with Profiler → GPU Usage and Frame Debugger. We count how many objects are rendered beyond visible detail. After the audit, we prepare an LOD specification: a table with object categories, level counts, threshold distances, and shadow policy per level. This artifact is agreed with the art team.

Implementation: either configure existing LOD Groups, create LOD assets (if absent), or auto-generate with manual fixes for critical objects.

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After an audit, we found 450 objects without LOD. We created LOD assets with 2–3 levels, applied cross-fade for buildings and instant for props. Result: FPS rose from 28 to 55 on a Samsung Galaxy S10. Draw call savings: 40%.

What's included in the work

Contact us for a consultation—we'll prepare a proposal for your project. Our engineers have experience setting up LOD for AAA projects and mobile games. Drop us a line, we'll assess your task in 1–2 days with no obligations.

What Are the Typical Game Performance Problems and How Optimization Solves Them?

A project runs smoothly on developer devices. On a five-year-old mid-range Android, it hits 20 fps and overheats after five minutes. On iPhone 11 it maintains 60 fps, but on iPhone XR it drops in heavy scenes. We encounter this every day. Optimization is not a later task—it is an architectural decision from the first commit. With eight years of experience, we have optimized over fifty games, from hypercasual to AAA on consoles. We guarantee: after our audit, you get not just a list of problems, but a concrete plan with measurable goals and deadlines. Order a performance audit — we evaluate your project in three days and show how to reduce draw calls by 40% without losing quality.

How to Profile Game Performance? Tools and Best Practices

Before any optimization, measure. Optimization without profiling is guesswork.

Profile on target hardware, not in the editor. The editor adds overhead — Play Mode numbers are not representative. Distinguish between GPU and CPU bottlenecks: CPU may cause many draw calls or heavy logic, GPU may have complex shaders or overdraw. Unity Documentation: profiling on device is mandatory for mobile games. Typical profiling time for one scenario is five to eight hours, including metrics collection on three to five devices of different generations.

How Does Game Performance Optimization Reduce Draw Calls? Static Batching to SRP Batcher

A draw call is a command from CPU to GPU to “draw this.” Each call has overhead regardless of geometry complexity. On mobile, 200–300 draw calls per frame is typical. The goal is to minimize their number by combining geometry that shares the same material.

Static Batching combines stationary meshes during build. Requirement: Static flag on objects and the same material. Effective for static environments but increases memory usage – the combined mesh is stored separately. In scenes with thousands of static objects, monitor memory via Memory Profiler.

Dynamic Batching combines meshes at runtime with strict limits: fewer than 900 vertex attributes per mesh, same material and scale. In practice, it works only for small objects (particles, UI). Disabled by default in URP – replaced by SRP Batcher.

SRP Batcher is not classic batching – it optimizes CPU overhead when preparing draw calls. Instead of reloading shader uniform data each frame, SRP Batcher caches it in GPU memory and updates only when changed. Draw calls remain the same in number, but each takes less CPU time – sometimes 2–3 times less on render CPU time compared to standard batching. Requirement: shader must be compatible with SRP Batcher (declare per-object properties in UnityPerDraw CBUFFER). Standard URP Lit/Unlit shaders are compatible. Custom ones – check in Material Inspector: SRP Batcher compatible: Yes/No. To enable, ensure the SRP Batcher option is active in URP Asset, and for custom shaders use UNITY_INSTANCING_BUFFER macro and declare per-object properties in CBUFFER_START(UnityPerDraw). After enabling, the RenderLoop.Draw CPU time should decrease in Profiler.

GPU Instancing is for many copies of the same mesh with the same material (trees, grass, NPCs). It sends one draw call with an array of per-instance data. Enable on material: Enable GPU Instancing. Limitation: all instances in one batch must have the same material and mesh. Graphics.DrawMeshInstanced / Graphics.DrawMeshInstancedIndirect enable procedural rendering without GameObject overhead.

The choice of method depends on scenario. Static Batching for static environments. SRP Batcher wins in projects with many unique materials. GPU Instancing is indispensable for mass objects (forests, crowds). Dynamic Batching only for small and rare cases. In practice, we combine all methods, starting with profiling.

For more details on the technology, see Geometry instancing (Wikipedia).

Why Is Memory Optimization Critical for Mobile Games?

Mobile platforms have strict RAM limits. iOS kills apps without warning on memory pressure. Android does similarly with onLowMemory callback. Target budgets: iOS <1 GB for modern devices, <512 MB for iPhone 8/X support; Android <800 MB for broad compatibility (OS uses 400–600 MB). Typical savings after our optimization are 30–50% of RAM while maintaining quality.

Addressables and Asset Bundles: How to Stay Within Budget

Loading everything at startup is unacceptable for large projects. Addressables (a wrapper over Asset Bundles) provide addressable asynchronous asset loading. Explicit unload: Addressables.ReleaseInstance / Addressables.Release. Addressables do not automatically unload assets when objects are destroyed. A common mistake: Addressables.InstantiateAsync in a loop without Release – memory grows until crash. Reference counting: an asset is unloaded only when all its handles are freed. Architectural pattern: a service/manager holds the handle of the loaded asset and releases it during scene transitions.

Groups and Bundle Strategy: group assets by loading logic. For example, all assets of one level in one bundle, shared assets (UI, fonts) in a separate group with Prevent Updates. This strategy saves up to 30% memory.

Texture Memory: Where 70% of RAM Comes From

Textures are the main memory consumer. Analyze via Memory Profiler: All Of Memory -> Texture2D shows the heaviest textures immediately. In practice, we find textures with inflated Max Size (4096 for a mobile icon is a typical mistake). Measures: Mipmap for 3D textures (enable), for UI (disable); Streaming Mipmaps for open world – loads mip levels as camera approaches. A common problem: textures referenced by unused Materials remain in memory – Memory Profiler shows the reference chain. Remove unnecessary materials. After replacing all RGBA32 textures with ASTC 6×6 on Android, savings reach 60% without quality loss.

GC Allocations: How to Eliminate Freezes in Hot Path

C# garbage collector in Unity is stop-the-world. If heap memory is allocated per frame, GC pause causes visible freezes. Goal: zero allocations in hot path (Update, FixedUpdate, render). Typical sources: string concatenation in Update (replace with StringBuilder); LINQ in hot path (manual loops with pre-allocated lists); GetComponent<T>() every frame (cache in Awake/Start); boxing value types when passed as object parameters. After profiling with Unity Profiler, we reduce hot path allocations by 95% – freezes disappear.

How Can LOD and Culling Cut 40% of Draw Calls?

LOD Group switches to simplified geometry as the object moves away from camera. Standard for 3D environment: LOD0 (100% triangles), LOD1 (30–50%), LOD2 (10–15%), Culled. For mobile, set Culled threshold more aggressively – draw less per frame.

Occlusion Culling – Unity does not render objects behind walls. Requires baked occlusion data. For indoor scenes, reduces draw calls by 20–40%.

Frustum Culling works automatically – objects outside camera FOV are not rendered. But the draw call for the check still happens. For scenes with thousands of objects, use custom spatial partitioning (Quadtree, Octree). In one of our projects, implementing occlusion culling and LOD reduced total draw calls from 2800 to 450 on Android.

How to Maintain 72 FPS on Quest 3 with VR Optimization?

VR is a separate class of tasks. Frame rate of 72 or 90 Hz must not be violated, or motion sickness occurs. In addition to standard methods: Single Pass Instanced Rendering – renders both eyes in one pass (halves draw calls); Fixed Foveated Rendering (Quest) – reduces peripheral resolution; Late Latching (Quest 3) – updates controller position as late as possible before rendering; Dynamic Resolution in URP/HDRP – automatically lowers render resolution on fps drops. For Quest, profile via OVR Metrics Tool – displays CPU/GPU time directly in headset. After applying these methods, frame rate on Quest 2 stabilizes at 72 FPS even in scenes with 1.5 million polygons.

What Deliverables Do You Get from Game Performance Optimization? Stages and Timelines

We offer a comprehensive turnkey service. Here is exactly what you receive:

1. Profiling report on target devices – metrics (FPS, draw calls, memory, GC) for 5–7 main scenarios. Delivery: 3–5 business days.
2. Priority action plan – which problems are critical, which can be deferred. Priorities based on impact on gaming experience.
3. Optimization implementation – batching, LOD, Addressables, shaders, occlusion culling. Average implementation cycle: 2–4 weeks.
4. Re-profiling results – measured improvements. Typical FPS increase: 30–60% on mobile devices.
5. Documentation – recommendations for maintenance and further development.
6. Team training – how to prevent regressions. We conduct workshops on profiling and optimization.

Get a consultation – we evaluate your project for free and show the optimization potential. Contact us to learn exact timelines and details for your stack.