Unreal Engine 5 Lumen and Nanite Low FPS

How to fix it

Try these in order — the most common fix is first.

1. 1. Profile correctly

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   1. Use a standalone or packaged build, run stat unit and stat gpu
   2. Do not judge from the editor viewport
   Did this fix it? Yes No

2. 2. Lower Lumen cost

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   1. Drop Global Illumination and Reflections quality in scalability
   2. Try r.Lumen.HardwareRayTracing=0 for software tracing
   3. Lower screen percentage or use upscaling
   Did this fix it? Yes No

3. 3. Review shadows and Nanite

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   1. Test shadow quality and Virtual Shadow Maps cost
   2. If a scene has no Nanite meshes, r.Nanite 0 reportedly saves some time
   Did this fix it? Yes No

4. 4. Consider alternatives

   1. For low-end and mobile targets, disable Lumen and use baked lighting
   Did this fix it? Yes No

Symptoms

UE5 project runs at low frame rates with Lumen and Nanite enabled, with big GPU time in Lumen, Virtual Shadow Maps or base pass.

Why it happens

• Lumen at Epic scalability is expensive (about 8 ms at 1080p on consoles per an Epic comment)
• Virtual Shadow Maps cost
• Hardware ray tracing enabled
• Profiling in editor rather than a packaged build
• Nanite on scenes without Nanite meshes or with masked foliage

This guide also covers

• unreal engine 5 low fps lumen
• nanite performance problems
• unreal engine 5 lumen too slow

Other Unreal Engine errors

• Unreal Engine Fatal Error Crash
• Unreal Engine GPU Crashed or D3D Device Removed
• Unreal Engine Shaders Compiling Forever (Stuck at 45%)
• Unreal Engine Out of Video Memory Error
• Unreal Engine Project Won't Open After Upgrade
• Epic Games Launcher Stuck Installing Unreal Engine
• Unreal Engine Packaging Failed (Unknown Cook Failure)
• Unreal Engine Visual Studio C++ Build Errors