diff --git a/BENCHMARKS.md b/BENCHMARKS.md
index 7e293f8..40dce34 100644
--- a/BENCHMARKS.md
+++ b/BENCHMARKS.md
@@ -177,3 +177,16 @@ the fleet doc's `m1max@` user and "disk-critical" note are both stale — 170GB
 Notable: 2nd-best bandwidth in the fleet (336 GB/s > M4 Pro's 225) despite mid-pack
 compute — good fit for memory-bound MLX work (VAE decode, big-tensor elementwise).
 Fleet total ≈ 66 TFLOPS fp16 across 7 machines.
+
+## 2026-07-19 — trellis_mac rung 1: sparse-conv backend verified (m3ultra, anatomy image, seed 42, 1024-cascade)
+
+| SPARSE_CONV_BACKEND | total gen+bake | wall | peak RSS |
+|---|---|---|---|
+| flex_gemm (Metal) | **124.8 s** | 248.8 s | 20.8 GB |
+| none (pure-torch) | 214.4 s | 337.6 s | 20.8 GB |
+
+Verdicts:
+- The 124.8s baseline WAS the Metal fast path (log line "[SPARSE] Conv backend: flex_gemm") — no hidden 10x jackpot; metallib loads fine on macOS 26.5.
+- Metal sparse-conv is worth **1.72x end-to-end** (saves 89.6s/gen). Keep flex_gemm the default; the conv_none fallback is a real 90s regression if the metallib ever breaks silently — worth a GODBOARD/log assertion.
+- Remaining fat in the fast path: ~46s diffusion sampling (padded SDPA attention — next kernel frontier), ~50s decode/extract (incl. aten::segment_reduce falling back to CPU — patchable), 19s Metal bake.
+- Decode actually produces 2.79M faces before the forced ~200k simplify — the quality-recovery headroom (rung 2) is bigger than the recon estimated.