keywords: UE5, Performance Optimization

The previous article: UE4 Performance Optimization

  1. Consider using test builds when profiling
    Test builds have lower overhead than Development, while still providing some developer functionality. Test builds of a stand-alone executable require cooked content. If you need to iterate while profiling, but want the lower CPU overhead of a Test build, consider using “cook on the fly” (COTF). For example, shader iteration is possible with COTF Test builds.
    Also note that in some older versions of Unreal Engine, you may have to manually enable the STATS macro in Build.h to add support for the stat GPU console command. Also, older versions of UE may require you to enable the ALLOW_PROFILEGPU_IN_TEST macro in Build.h so that the ProfileGPU command is available. More details will be given on stat GPU and ProfileGPU in the Profiling tools section.

Origin:Unreal Engine Performance Guide


The key parameters that reduce effects to improve performance:


Experiment with reducing this value from the default of 8. The visual difference between any two adjacent values, e.g., 7 and 8, is nearly imperceptible. However, the performance benefit will not go unnoticed, especially in scenes with lots of shadow casting lights:


The corresponding SamplesPerRayDirectional has similarly low impact on visual fidelity, but only improves performance on your directional lights (e.g. sun, moon, etc.), which are generally less prevalent in most game levels. Thus modification of this parameter has less of an impact on performance.


Origin:Unreal Engine Performance Guide


If GPUScene::Update takes a long time, it may be that the mesh has many UV seams.
Reference: Performance hit “GPU scene update” - reddit


UE5 Skeleton (Bone) Vertex Animation Texture example.


Optimizing UE5: Rethinking Performance Paradigms for High-Quality Visuals Pt.1: Nanite and Lumen - Matt Oztalay, Epic Games

Optimizing UE5: Rethinking Performance Paradigms for High-Quality Visuals - Pt.2: Supporting Systems - Matt Oztalay, Epic Games

Unreal Engine Performance guide

Behave toward everyone as if receiving a guest. -Chinese Proverbs