Game-thread performance

The game thread is the main bottleneck for many Unreal projects: it owns actor ticking, Blueprint execution, input, physics callbacks, and UI updates. If the game thread misses its per-frame budget, the frame is delayed even when the GPU is idle.

When to use this skill

• Frame rate feels low but the GPU looks underused.
• stat unit or stat game shows the Game thread dominating the frame.
• Tick-heavy actors, Blueprint hot paths, or frequent Tick() work are causing hitches.
• You need a quick mental model for how game-thread time translates into FPS.

Mental model: frame budget is fixed

The hard ceiling for one frame is 1000 / TargetFPS milliseconds, so every extra millisecond of game-thread work costs real frame time: