Live profiling found the dense-town (Arwic 29fps) bottleneck: EnvCellRenderer
.Render called ~94x/frame (per-cell x opaque+transparent) = 24.75ms = 75% of
the GPU frame. Render is a heavy per-frame method (state reset + SSBO upload +
MDI) invoked per-cell for far->near transparency order. Eliminated, with
evidence, every other suspect incl. the handoff's distance-degrade theory
(entities 0.22ms; resolution-independent => not fill; update 0.1ms).
Spec: batch the shell draws into one Render per pass. Opaque needs no order
(z-buffer) + lighting is per-instance (CellId-keyed SSBO) => safe to batch.
Transparent: skip opaque-only cells, preserve order for the rest.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>