Tomba2 16:9 GL reproduced the reported collapse (12-14fps) and the GPU-side
split EXONERATED the GPU: scene_gpu ~10ms, mirror ~0.2ms, while emu_cpu is
~82ms (vs ~15ms in squash). gl_ws_ablate=1 (mirror passes fully off) leaves
it at ~75ms, so the wedge is CPU work outside the mirror draws. The GL
submission paths run INSIDE guest emulation (GP0/DMA processing), so driver
CPU cost lands in emu_cpu where no GPU timer sees it.
frame_perf now reports, per wide/4:3 frame class: CPU wall inside
flush_tex_batch (cpu_flush_ms_avg), CPU wall inside the glb_wide_* entry
points (cpu_wide_ms_avg), batches/frame, wide target sets/frame, and wide
FBO creations/frame (a nonzero steady value = surface recreation churn).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Matthew Stanley
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