GPU and render thread

Attribute GPU cost

1. Confirm GPU is plausibly the bound with stat unit.
2. Run stat gpu for a live overview.
3. Capture one representative frame with profilegpu or Ctrl+Shift+;.
4. Expand the event tree from the largest millisecond pass to its children.
5. Repeat at the same camera, resolution, screen percentage, and quality.
6. Toggle one supported renderer feature or quality control and compare the same pass.

GPU time may contain idle time. Asynchronous compute overlaps passes, so individual event totals can overlap or appear inflated. Disable async compute only for isolated diagnosis when Epic's subsystem guide explicitly recommends it; restore it for the real end-to-end measurement.

Separate submission from shading

Evidence	Likely direction
Draw/Render thread dominates, many primitives/sections	reduce submissions, components, sections, visibility work
GPU base pass dominates	material/pixel coverage/geometry path
shadows dominate	light/shadow method, invalidation, caster coverage
translucency/post dominates	screen coverage, layer count, resolution, effect quality
lowering resolution helps strongly	pixel-bound passes/upscaler tradeoff
lowering resolution barely helps	geometry/submission/CPU or fixed-cost GPU work

Use the rendering-performance skill only after the pass or submission cost is identified.