Ошибка	Последствие
Оптимизировать без `stat unit`	Тратите время не на то узкое место; FPS не меняется
Складывать `Game + Draw + GPU`	Это параллельные потоки, кадр = `max`, а не сумма
Оставлять `bCanEverTick = true` по умолчанию для всех акторов	Тысячи пустых тиков съедают game thread
Спавнить projectile через `SpawnActor` каждый выстрел	Тяжёлые аллокации, GC давление; нужен пул
Ставить dynamic point light без необходимости	Каждый источник с тенями — отдельный shadow pass на GPU
Использовать `StaticMeshComponent` для 5000 камней	Каждый — отдельный draw call; нужен `HISM`
Делать `Event Tick` в UMG-виджете	Перерисовка слоя UI каждый кадр; нужен delegate-driven update
Считать LOD автоматическим для любого меша	LOD'ы должны быть созданы для конкретного ассета
Тестировать GPU bottleneck на 4K без `r.ScreenPercentage`	Не отделяете влияние разрешения от шейдеров
`LineTraceByChannel` каждый кадр на каждом враге	Десятки запросов в physics scene; кэшируйте, фильтруйте
Думать, что `Destroy()` сразу освобождает память	Объект попадает в GC, освобождение отложено до следующего цикла
Профилировать в редакторе и делать выводы про packaged build	Editor содержит overhead инструментов и slate, цифры нерелевантны

advanced

Unreal Performance

stat unit, Tick optimization, draw calls, LOD/culling/instancing, lighting cost, UI and object pooling — the UE performance methodology.

ue-performance

Practice: 22 questions · 2 tasks →

Sections

Contents

Detailed explanation

Unreal Performance — `stat unit` first, optimization after

Performance in Unreal is a methodology, not a bag of tricks. The right order is: measure → identify the bottleneck → optimize that specific thing → measure again. Any deviation is guessing. People who optimize "everything" without stat unit waste days on edits that don't move the FPS.

A frame in Unreal runs in parallel on three threads: the game thread (logic, Tick, AI, Blueprints), the render thread (Draw — culling, draw-call setup, command submission), and the GPU (rasterization, shading, post-processing). Frame time is the max of the three, not the sum. So speeding up the GPU on a game-bound frame buys you nothing: the bottleneck is elsewhere.

The most common mistake is "my FPS is low, buy a better GPU" or "let's optimize the materials". Without stat unit you can't know who's at fault. It might be one Actor with a heavy Tick; it might be 5000 unique draw calls; it might be two dynamic point lights with shadow maps. Each cause has a different cure. This topic teaches you to tell them apart and pick the right tool.

Topic map

Profiling tools — stat unit, stat gpu, Unreal Insights, GPU Profiler, command-line -trace=.
CPU vs GPU bound — identifying the bottleneck, what "Game/Draw/GPU dominates" means, r.ScreenPercentage as a test.
Tick optimization — bCanEverTick, SetActorTickEnabled, TickInterval, TickGroup, replacing Tick with delegates and timers.
Draw calls — what they are, why the Draw thread issues them, batching, instancing, material instances.
LOD system — distance/screen-size LODs, HLOD, proxy meshes, World Partition and stream-out.
Culling — frustum culling, occlusion, distance culling, cull distance volumes, dithered LOD transitions.
Instancing — ISM, HISM, vs StaticMeshComponent, when to use, limitations.
Lighting cost — static/stationary/movable, dynamic shadows, light count, shadow casting, virtual shadow maps.
UI performance — UMG invalidation, Invalidation Box, Retainer Box, widget hierarchy, replacing Tick with delegates.
Object pooling — the pool pattern, why Spawn/Destroy is expensive, projectile/VFX implementation.
Collision optimization — TraceChannel, simple vs complex, NoCollision, filters, queries vs physics.
Memory profiling — memreport, LLM, Memory Insights, GC cost and ForceGarbageCollection.

Common traps

Mistake	Consequence
Optimizing without running `stat unit`	You fix the wrong bottleneck; FPS doesn't move
Adding `Game + Draw + GPU`	They run in parallel; frame time is `max`, not sum
Leaving `bCanEverTick = true` by default on every actor	Thousands of empty ticks eat the game thread
Spawning a projectile via `SpawnActor` every shot	Heavy allocations, GC pressure; you need a pool
Using a dynamic point light when not needed	Each shadowed light is a separate shadow pass on the GPU
Using `StaticMeshComponent` for 5000 rocks	Each is its own draw call; you need `HISM`
Putting `Event Tick` in a UMG widget	UI redrawn every frame; use delegate-driven updates
Assuming LODs are automatic for any mesh	LODs must be authored for the specific asset
Testing GPU bottleneck at 4K without `r.ScreenPercentage`	You can't separate resolution from shader cost
`LineTraceByChannel` every frame on every enemy	Dozens of physics-scene queries; cache, filter
Thinking `Destroy()` frees memory immediately	The object goes to GC; release is deferred to the next cycle
Profiling in editor and drawing conclusions about packaged builds	Editor includes tool/slate overhead; numbers are irrelevant

Interview relevance

Performance is a senior-level topic. Interviewers check:

Knowledge of stat unit and interpreting the three threads (Game/Draw/GPU).
The canonical loop: profile → bottleneck → targeted fix → re-measure.
Distinguishing CPU-bound from GPU-bound and proposing different fixes.
Why ISM/HISM reduces draw calls, not "GPU work in general".
The cost of dynamic shadows vs static lights.
The pool pattern and why SpawnActor is expensive.

Common wrong answer: "I optimize materials, set up LODs, and the game runs fast." Real answer — without diagnostics you don't know what the bottleneck is. A scene with 200 dynamic lights and one material doesn't have a material problem; a scene with 50000 unique meshes without LODs doesn't have a lighting problem. stat unit first, the conversation second.

Why it matters

Without the "profile → bottleneck → targeted fix" loop, optimization becomes guesswork. People who don't know `stat unit` and the three threads — Game/Draw/GPU — optimize the wrong things in the wrong places.

Ошибка	Последствие
Оптимизировать без `stat unit`	Тратите время не на то узкое место; FPS не меняется
Складывать `Game + Draw + GPU`	Это параллельные потоки, кадр = `max`, а не сумма
Оставлять `bCanEverTick = true` по умолчанию для всех акторов	Тысячи пустых тиков съедают game thread
Спавнить projectile через `SpawnActor` каждый выстрел	Тяжёлые аллокации, GC давление; нужен пул
Ставить dynamic point light без необходимости	Каждый источник с тенями — отдельный shadow pass на GPU
Использовать `StaticMeshComponent` для 5000 камней	Каждый — отдельный draw call; нужен `HISM`
Делать `Event Tick` в UMG-виджете	Перерисовка слоя UI каждый кадр; нужен delegate-driven update
Считать LOD автоматическим для любого меша	LOD'ы должны быть созданы для конкретного ассета
Тестировать GPU bottleneck на 4K без `r.ScreenPercentage`	Не отделяете влияние разрешения от шейдеров
`LineTraceByChannel` каждый кадр на каждом враге	Десятки запросов в physics scene; кэшируйте, фильтруйте
Думать, что `Destroy()` сразу освобождает память	Объект попадает в GC, освобождение отложено до следующего цикла
Профилировать в редакторе и делать выводы про packaged build	Editor содержит overhead инструментов и slate, цифры нерелевантны

advanced

Unreal Performance

stat unit, Tick optimization, draw calls, LOD/culling/instancing, lighting cost, UI and object pooling — the UE performance methodology.

ue-performance

Practice: 22 questions · 2 tasks →

Sections

Contents

Detailed explanation

Unreal Performance — `stat unit` first, optimization after

Topic map

Profiling tools — stat unit, stat gpu, Unreal Insights, GPU Profiler, command-line -trace=.
CPU vs GPU bound — identifying the bottleneck, what "Game/Draw/GPU dominates" means, r.ScreenPercentage as a test.
Tick optimization — bCanEverTick, SetActorTickEnabled, TickInterval, TickGroup, replacing Tick with delegates and timers.
Draw calls — what they are, why the Draw thread issues them, batching, instancing, material instances.
LOD system — distance/screen-size LODs, HLOD, proxy meshes, World Partition and stream-out.
Culling — frustum culling, occlusion, distance culling, cull distance volumes, dithered LOD transitions.
Instancing — ISM, HISM, vs StaticMeshComponent, when to use, limitations.
Lighting cost — static/stationary/movable, dynamic shadows, light count, shadow casting, virtual shadow maps.
UI performance — UMG invalidation, Invalidation Box, Retainer Box, widget hierarchy, replacing Tick with delegates.
Object pooling — the pool pattern, why Spawn/Destroy is expensive, projectile/VFX implementation.
Collision optimization — TraceChannel, simple vs complex, NoCollision, filters, queries vs physics.
Memory profiling — memreport, LLM, Memory Insights, GC cost and ForceGarbageCollection.

Common traps

Mistake	Consequence
Optimizing without running `stat unit`	You fix the wrong bottleneck; FPS doesn't move
Adding `Game + Draw + GPU`	They run in parallel; frame time is `max`, not sum
Leaving `bCanEverTick = true` by default on every actor	Thousands of empty ticks eat the game thread
Spawning a projectile via `SpawnActor` every shot	Heavy allocations, GC pressure; you need a pool
Using a dynamic point light when not needed	Each shadowed light is a separate shadow pass on the GPU
Using `StaticMeshComponent` for 5000 rocks	Each is its own draw call; you need `HISM`
Putting `Event Tick` in a UMG widget	UI redrawn every frame; use delegate-driven updates
Assuming LODs are automatic for any mesh	LODs must be authored for the specific asset
Testing GPU bottleneck at 4K without `r.ScreenPercentage`	You can't separate resolution from shader cost
`LineTraceByChannel` every frame on every enemy	Dozens of physics-scene queries; cache, filter
Thinking `Destroy()` frees memory immediately	The object goes to GC; release is deferred to the next cycle
Profiling in editor and drawing conclusions about packaged builds	Editor includes tool/slate overhead; numbers are irrelevant

Interview relevance

Performance is a senior-level topic. Interviewers check:

Knowledge of stat unit and interpreting the three threads (Game/Draw/GPU).
The canonical loop: profile → bottleneck → targeted fix → re-measure.
Distinguishing CPU-bound from GPU-bound and proposing different fixes.
Why ISM/HISM reduces draw calls, not "GPU work in general".
The cost of dynamic shadows vs static lights.
The pool pattern and why SpawnActor is expensive.

Why it matters

Производительность Unreal

Производительность Unreal — `stat unit` сначала, оптимизация потом

Карта темы

Частые ошибки и ловушки

Значение для собеседований

Unreal Performance

Unreal Performance — `stat unit` first, optimization after

Topic map

Common traps

Interview relevance

Производительность Unreal

Производительность Unreal — `stat unit` сначала, оптимизация потом

Карта темы

Частые ошибки и ловушки

Значение для собеседований

Unreal Performance

Unreal Performance — `stat unit` first, optimization after

Topic map

Common traps

Interview relevance

Unreal Performance

Unreal Performance — stat unit first, optimization after

Topic map

Common traps

Interview relevance

Unreal Performance

Unreal Performance — stat unit first, optimization after

Topic map

Common traps

Interview relevance

Unreal Performance — `stat unit` first, optimization after

Unreal Performance — `stat unit` first, optimization after