Always-on per-frame ring in the GL renderer: two GL_TIME_ELAPSED queries
bracket each frame's scene draws vs the present clear+blit (true GPU time,
independent of CPU/GPU overlap), plus SDL perf-counter CPU wall time
(present-to-present total, present call). Exposed via the debug server
"frame_perf" command, aggregated over the recent ring and split by 4:3 vs
native-wide so a 16:9-vs-4:3 A/B reads off one query.
Built to answer where a frame goes without guessing. First use proved
Tomba's 16:9 village lag is the native-wide DOUBLE-DRAW (every primitive
re-issued into the wide FBO), NOT supersampling (SS2==SS1) and NOT the
compositor (present_gpu ~1ms): scene_gpu 16:9=28ms vs 4:3=17ms.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Matthew Stanley
1e3244db4a