bench: jetson FPS battery — both backends saturate at 80.9 MB scale

Parameterizes the throttle-sweep FPS battery (fpsBattery helper) and adds a
jetson-agx-thor run: asyncify raf 2.1-5.3 / distinct 0.2-0.8 vs JSPI raf
1.9-5.0 / distinct 0.1-0.7 — indistinguishable. Suspension overhead is a
per-event-loop-turn cost; at hundreds of ms of GAL work per frame it stops
discriminating. vme-wren (~27 MB) remains the discriminating size class.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016X9eh1s5sTx1o9Em9KBuwR

docs/features/async/migration-evidence/bench-data-2026-08/perf-bench-asyncify.ndjson

@@ -18,3 +18,10 @@
 {"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T09:48:29.439Z","section":"fps-vme","throttle":6,"rep":2,"rafFps":34.3,"distinctFps":2.8}
 {"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T09:48:29.442Z","section":"fps-vme-postmem","postFpsMem":{"wasmHeapBytes":962330624,"jsHeapBytes":60300000}}
 {"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T09:48:46.855Z","section":"open-jetson","bytes":84806775,"outcome":"loaded","openMs":14584,"openPeakHeap":1904214016,"postOpenMem":{"wasmHeapBytes":1904214016,"jsHeapBytes":116000000}}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:05:39.841Z","section":"fps-jetson","throttle":1,"rep":1,"rafFps":4.4,"distinctFps":0.5}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:05:46.092Z","section":"fps-jetson","throttle":1,"rep":2,"rafFps":5.3,"distinctFps":0.8}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:05:52.980Z","section":"fps-jetson","throttle":4,"rep":1,"rafFps":2.1,"distinctFps":0.4}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:06:00.712Z","section":"fps-jetson","throttle":4,"rep":2,"rafFps":3.4,"distinctFps":0.6}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:06:06.843Z","section":"fps-jetson","throttle":6,"rep":1,"rafFps":2.5,"distinctFps":0.2}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:06:14.282Z","section":"fps-jetson","throttle":6,"rep":2,"rafFps":3.9,"distinctFps":0.7}
+{"arm":"asyncify","sha256":"6dab493196d060d7","when":"2026-08-14T10:06:14.285Z","section":"fps-jetson-postmem","postFpsMem":{"wasmHeapBytes":1904214016,"jsHeapBytes":177000000}}

docs/features/async/migration-evidence/bench-data-2026-08/perf-bench-jspi.ndjson

@@ -25,3 +25,10 @@
 {"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T09:52:24.000Z","section":"fps-vme","throttle":6,"rep":1,"rafFps":34.3,"distinctFps":3.3,"note":"glcanvas sampler re-run; when approximate"}
 {"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T09:52:30.000Z","section":"fps-vme","throttle":6,"rep":2,"rafFps":41.8,"distinctFps":5.3,"note":"glcanvas sampler re-run; when approximate"}
 {"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T09:52:30.100Z","section":"fps-vme-postmem","postFpsMem":{"wasmHeapBytes":801898496,"jsHeapBytes":64000000}}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:14.509Z","section":"fps-jetson","throttle":1,"rep":1,"rafFps":5,"distinctFps":0.7}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:21.557Z","section":"fps-jetson","throttle":1,"rep":2,"rafFps":4.1,"distinctFps":0.7}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:32.709Z","section":"fps-jetson","throttle":4,"rep":1,"rafFps":2.3,"distinctFps":0.4}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:40.639Z","section":"fps-jetson","throttle":4,"rep":2,"rafFps":1.9,"distinctFps":0.1}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:48.685Z","section":"fps-jetson","throttle":6,"rep":1,"rafFps":2.1,"distinctFps":0.1}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:55.534Z","section":"fps-jetson","throttle":6,"rep":2,"rafFps":4.3,"distinctFps":0.3}
+{"arm":"jspi","sha256":"6f03e62d6d5619c3","when":"2026-08-14T10:04:55.537Z","section":"fps-jetson-postmem","postFpsMem":{"wasmHeapBytes":1730805760,"jsHeapBytes":157000000}}

docs/features/async/migration-evidence/jspi-vs-asyncify-bench-2026-08.md

@@ -156,6 +156,16 @@ The distinct-frame gap grows from +21 % at 1× to +68 % at 4× — the same
 "advantage widens under throttle" signature doc-12 used to prove lower
 CPU-per-operation (as opposed to just a smaller module).
 
+**FPS on jetson-agx-thor (80.9 MB)** — added 2026-08-14 pm: at this scale BOTH
+arms saturate outright and the backend difference disappears into noise
+(asyncify raf 2.1–5.3 / distinct 0.2–0.8; JSPI raf 1.9–5.0 / distinct
+0.1–0.7; post-FPS heap 1.90 vs 1.73 GB). With <1 real redraw/s the 6 s
+windows count 1–5 frames, i.e. quantization noise. Reading: suspension
+overhead is a per-event-loop-turn cost — once per-frame GAL/geometry work is
+hundreds of ms, it no longer discriminates. vme-wren (~27 MB) is the size
+class where the backend visibly matters for interaction; jetson is the
+"both need render-side optimization" regime.
+
 **Memory checkpoints** (wasm linear memory; Chromium `usedJSHeapSize` tracked
 alongside, differences <10 %): boot 557 vs 387 MB; after vme-wren open 962 vs
 802 MB; unchanged after the FPS sweep on both arms.

tests/kicad/pcbnew-large-perf.spec.ts

@@ -118,11 +118,18 @@ test.describe('pcbnew large-board bench', () => {
         });
     }
 
-    test('FPS on vme-wren across throttles', async ({ page, testLogger }) => {
+    // Shared throttle-sweep FPS battery: load editor, fetch+open the board,
-        test.setTimeout(900000);
+    // then rAF + distinct-glcanvas-frame FPS at each throttle rate.
+    async function fpsBattery(
+        page: Parameters<Parameters<typeof test>[2]>[0]['page'],
+        testLogger: { consoleLogs: string[]; errors: string[] },
+        boardUrl: string,
+        memfsPath: string,
+        section: string,
+    ): Promise<void> {
         await measureLoad(page, '/kicad/pcbnew.html');
-        await fetchIntoMemfs(page, VME_URL, '/home/kicad/documents/vme-wren.kicad_pcb');
+        await fetchIntoMemfs(page, boardUrl, memfsPath);
-        await openAndWait(page, '/home/kicad/documents/vme-wren.kicad_pcb', 'board', testLogger, 480000);
+        await openAndWait(page, memfsPath, 'board', testLogger, 780000);
         await page.keyboard.press('Escape').catch(() => {}); // eslint-disable-line -- best-effort Escape
 
         const cdp = await page.context().newCDPSession(page);
@@ -130,13 +137,29 @@ test.describe('pcbnew large-board bench', () => {
             await setThrottle(cdp, rate);
             for (let rep = 0; rep < FPS_REPS; rep++) {
                 const f = await measureFpsDetailed(page, FPS_SECS);
-                record('fps-vme', { throttle: rate, rep: rep + 1, ...f });
+                record(section, { throttle: rate, rep: rep + 1, ...f });
                 expect(f.rafFps).toBeGreaterThan(0);
             }
         }
         await setThrottle(cdp, 1);
         const mem = await sampleMemory(page);
-        record('fps-vme-postmem', { postFpsMem: mem });
+        record(`${section}-postmem`, { postFpsMem: mem });
+    }
+
+    test('FPS on vme-wren across throttles', async ({ page, testLogger }) => {
+        test.setTimeout(900000);
+        await fpsBattery(page, testLogger, VME_URL, '/home/kicad/documents/vme-wren.kicad_pcb', 'fps-vme');
+    });
+
+    test('FPS on jetson-agx-thor across throttles', async ({ page, testLogger }) => {
+        test.setTimeout(900000);
+        await fpsBattery(
+            page,
+            testLogger,
+            JETSON_URL,
+            '/home/kicad/documents/jetson-agx-thor-baseboard.kicad_pcb',
+            'fps-jetson',
+        );
     });
 
     test('open jetson-agx-thor (80.9 MB) — outcome, OOM allowed', async ({ page, testLogger }) => {