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WIP: benchmark prewarm, measure variance#3107

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⚠️ No Changeset found

Latest commit: f6f71c9

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The latest updates on your projects. Learn more about Vercel for GitHub.

Project Deployment Actions Updated (UTC)
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🧪 E2E Test Results

All tests passed

E2E Test Summary

Summary
Passed Failed Skipped Total
✅ ▲ Vercel Production 1455 0 239 1694
✅ 💻 Local Development 1621 0 227 1848
✅ 📦 Local Production 1621 0 227 1848
✅ 🐘 Local Postgres 1621 0 227 1848
✅ 📋 Other 1020 0 212 1232
✅ vercel-multi-region 27 0 0 27
Total 7365 0 1132 8497
Details by Category

✅ ▲ Vercel Production

App Passed Failed Skipped
✅ astro 126 0 28
✅ example 126 0 28
✅ express 126 0 28
✅ fastify 126 0 28
✅ hono 126 0 28
✅ nextjs-turbopack 151 0 3
✅ nextjs-webpack 151 0 3
✅ nitro 126 0 28
✅ nuxt 126 0 28
✅ sveltekit 145 0 9
✅ vite 126 0 28

✅ 💻 Local Development

App Passed Failed Skipped
✅ astro-stable 128 0 26
✅ express-stable 128 0 26
✅ fastify-stable 128 0 26
✅ hono-stable 128 0 26
✅ nextjs-turbopack-canary 135 0 19
✅ nextjs-turbopack-stable 154 0 0
✅ nextjs-webpack-canary 135 0 19
✅ nextjs-webpack-stable 154 0 0
✅ nitro-stable 128 0 26
✅ nuxt-stable 128 0 26
✅ sveltekit-stable 147 0 7
✅ vite-stable 128 0 26

✅ 📦 Local Production

App Passed Failed Skipped
✅ astro-stable 128 0 26
✅ express-stable 128 0 26
✅ fastify-stable 128 0 26
✅ hono-stable 128 0 26
✅ nextjs-turbopack-canary 135 0 19
✅ nextjs-turbopack-stable 154 0 0
✅ nextjs-webpack-canary 135 0 19
✅ nextjs-webpack-stable 154 0 0
✅ nitro-stable 128 0 26
✅ nuxt-stable 128 0 26
✅ sveltekit-stable 147 0 7
✅ vite-stable 128 0 26

✅ 🐘 Local Postgres

App Passed Failed Skipped
✅ astro-stable 128 0 26
✅ express-stable 128 0 26
✅ fastify-stable 128 0 26
✅ hono-stable 128 0 26
✅ nextjs-turbopack-canary 135 0 19
✅ nextjs-turbopack-stable 154 0 0
✅ nextjs-webpack-canary 135 0 19
✅ nextjs-webpack-stable 154 0 0
✅ nitro-stable 128 0 26
✅ nuxt-stable 128 0 26
✅ sveltekit-stable 147 0 7
✅ vite-stable 128 0 26

✅ 📋 Other

App Passed Failed Skipped
✅ e2e-local-dev-nest-stable 128 0 26
✅ e2e-local-dev-tanstack-start- 128 0 26
✅ e2e-local-postgres-nest-stable 128 0 26
✅ e2e-local-postgres-tanstack-start- 128 0 26
✅ e2e-local-prod-nest-stable 128 0 26
✅ e2e-local-prod-tanstack-start- 128 0 26
✅ e2e-vercel-prod-nest 126 0 28
✅ e2e-vercel-prod-tanstack-start 126 0 28

✅ vercel-multi-region

App Passed Failed Skipped
✅ nextjs-turbopack 27 0 0

📋 View full workflow run

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📊 Workflow Benchmarks

commit f6f71c9 · Sat, 25 Jul 2026 22:51:31 GMT · run logs

Backend: vercel · app: nextjs-turbopack

Metric Scenario Best (ms) P75 (ms) P90 (ms) P99 (ms) Samples
TTFS step 1427 (+13%) 1497 🔴 (+12%) 1507 🔴 (+10%) 1526 🔴 (+4.2%) 30
TTFS stream 254 (-32%) 💚 1491 🔴 (+11%) 1518 🔴 (+12%) 1654 🔴 (+19%) 🔻 30
TTFS hook + stream 1460 (+175%) 🔻 1592 🔴 (-13%) 1634 🔴 (-70%) 💚 1779 🔴 (-81%) 💚 30
STSO 1020 steps (1-20) 176 (-4.3%) 296 🔴 (-4.5%) 414 🔴 (-6.8%) 469 🔴 (+1.7%) 19
STSO 1020 steps (101-120) 190 (+7.3%) 277 🔴 (-1.1%) 316 🔴 (-11%) 397 🔴 (+9.7%) 19
STSO 1020 steps (1001-1020) 544 (+7.1%) 661 🔴 (-0.6%) 708 🔴 (-2.2%) 879 🔴 (+12%) 19
WO 1020 steps 422728 (-0.7%) 422728 (-0.7%) 422728 (-0.7%) 422728 (-0.7%) 1
SL stream latency 104 (+7.2%) 159 🔴 (-17%) 💚 175 🔴 (-49%) 💚 241 🔴 (-40%) 💚 30
SO stream overhead (text) 116 (-4.1%) 159 (-24%) 💚 207 (-24%) 💚 261 (-90%) 💚 30
SO stream overhead (structured) 111 (-5.1%) 168 (-3.4%) 251 (+31%) 🔻 479 (+69%) 🔻 30
📜 Previous results (3)

f6f71c9

Sat, 25 Jul 2026 06:57:29 GMT · run logs

vercel / nextjs-turbopack

Metric Scenario Best (ms) P75 (ms) P90 (ms) P99 (ms) Samples
TTFS step 1268 (-0.9%) 1318 🔴 (-4.2%) 1338 🔴 (-4.5%) 1403 🔴 (-4.8%) 30
TTFS stream 1260 (+290%) 🔻 1323 🔴 (-2.4%) 1368 🔴 (±0%) 1411 🔴 (-7.8%) 30
TTFS hook + stream 1464 (+6.7%) 1599 🔴 (-1.7%) 1687 🔴 (±0%) 1754 🔴 (±0%) 30
STSO 1020 steps (1-20) 162 (-2.4%) 301 🔴 (+19%) 🔻 349 🔴 (+20%) 🔻 534 🔴 (+70%) 🔻 19
STSO 1020 steps (101-120) 175 (-6.4%) 234 🔴 (-1.3%) 291 🔴 (+8.6%) 293 🔴 (-30%) 💚 19
STSO 1020 steps (1001-1020) 483 (-4.7%) 538 🔴 (-11%) 596 🔴 (-7.0%) 738 🔴 (+14%) 19
WO 1020 steps 386778 (-5.2%) 386778 (-5.2%) 386778 (-5.2%) 386778 (-5.2%) 1
SL stream latency 102 (-3.8%) 158 🔴 (-25%) 💚 181 🔴 (-46%) 💚 3783 🔴 (+700%) 🔻 30
SO stream overhead (text) 112 (-2.6%) 177 (+11%) 204 (-14%) 392 (+37%) 🔻 30
SO stream overhead (structured) 105 (-7.9%) 156 (-5.5%) 241 (+24%) 🔻 294 (-3.3%) 30

f6f71c9

Sat, 25 Jul 2026 05:51:31 GMT · run logs

vercel / nextjs-turbopack

Metric Scenario Best (ms) P75 (ms) P90 (ms) P99 (ms) Samples
TTFS step 1191 (-0.8%) 1281 🔴 (+1.0%) 1296 🔴 (±0%) 1390 🔴 (-1.3%) 30
TTFS stream 1205 (+404%) 🔻 1257 🔴 (-11%) 1271 🔴 (-11%) 1336 🔴 (-14%) 30
TTFS hook + stream 1465 (+1.1%) 1537 🔴 (-11%) 1669 🔴 (-5.7%) 1749 🔴 (-2.7%) 30
STSO 1020 steps (1-20) 154 (-9.4%) 227 🔴 (-12%) 286 🔴 (-33%) 💚 301 🔴 (-43%) 💚 19
STSO 1020 steps (101-120) 178 (-5.8%) 220 🔴 (-6.4%) 252 🔴 (-13%) 313 🔴 (-14%) 19
STSO 1020 steps (1001-1020) 470 (+1.5%) 732 🔴 (+8.6%) 3812 🔴 (+399%) 🔻 4372 🔴 (+35%) 🔻 19
WO 1020 steps 379966 (+1.4%) 379966 (+1.4%) 379966 (+1.4%) 379966 (+1.4%) 1
SL stream latency 92 (-1.1%) 132 🔴 (-9.6%) 153 🔴 (+0.7%) 273 🔴 (-26%) 💚 30
SO stream overhead (text) 99 (-1.0%) 163 (+6.5%) 186 (+9.4%) 333 (+38%) 🔻 30
SO stream overhead (structured) 97 (-4.9%) 142 (-6.0%) 175 (+10%) 231 (-51%) 💚 30

f6f71c9

Sat, 25 Jul 2026 00:40:46 GMT · run logs

vercel / nextjs-turbopack

Metric Scenario Best (ms) P75 (ms) P90 (ms) P99 (ms) Samples
TTFS step 1263 (+466%) 🔻 1312 🔴 (-0.8%) 1341 🔴 (-3.5%) 1441 🔴 (-16%) 💚 30
TTFS stream 1252 (+461%) 🔻 1318 🔴 (+0.8%) 1331 🔴 (+1.0%) 1372 🔴 (±0%) 30
TTFS hook + stream 1447 (+284%) 🔻 1583 🔴 (+3.5%) 1606 🔴 (-2.4%) 1742 🔴 (-1.5%) 30
STSO 1020 steps (1-20) 157 (-13%) 318 🔴 (+8.2%) 372 🔴 (+11%) 402 🔴 (-8.0%) 19
STSO 1020 steps (101-120) 195 (-4.9%) 294 🔴 (+7.3%) 410 🔴 (+7.3%) 581 🔴 (+34%) 🔻 19
STSO 1020 steps (1001-1020) 492 (+2.5%) 563 🔴 (+4.5%) 586 🔴 (+5.2%) 609 🔴 (+5.7%) 19
WO 1020 steps 403140 (±0%) 403140 (±0%) 403140 (±0%) 403140 (±0%) 1
SL stream latency 102 (+11%) 158 🔴 (-3.1%) 165 🔴 (-8.8%) 207 🔴 (-15%) 💚 30
SO stream overhead (text) 117 (+5.4%) 221 (+23%) 🔻 249 (+9.7%) 785 (+171%) 🔻 30
SO stream overhead (structured) 126 (+8.6%) 193 (-11%) 293 (-4.2%) 2545 🔴 (+507%) 🔻 30
ℹ️ Metric definitions & methodology

Best/P75/P90/P99 deltas compare two back-to-back runs of this same commit against the same deployment, so they reflect run-to-run benchmark noise rather than a change vs main. 🔻 flags a delta worse than +15%, 💚 one better than −15%.

Metrics — TTFS: time to first step body (in-deployment start() → first step body, deployment clocks) · STSO: step-to-step overhead (gap between consecutive step bodies) · WO: workflow overhead (whole-run time outside step bodies, in-deployment anchored) · SL: stream latency (in-deployment write → read propagation, readAt - writtenAt) · SO: stream overhead (end-to-end write+consume time beyond the modelled generation window)

Scenarios — step: one trivial no-op step, no stream; no hooks, so the run stays in turbo mode (in-process fast path) · stream: one streaming step; no hooks, so the run stays in turbo mode (in-process fast path) · hook + stream: registers a hook before one step, which exits turbo mode (dispatch path) · 1020 steps: 1020 trivial sequential steps; STSO is measured between consecutive steps in the given step ranges, and WO is the whole-run overhead outside step bodies · stream latency: parallel reader/writer steps on a dedicated stream; SL is the in-deployment write->read propagation (readAt - writtenAt) · stream overhead (text): writer streams 300 variable-length text token deltas paced at 100/s for 3s (a haiku-size LLM's token throughput) while a parallel reader drains the whole stream; SO is the end-to-end write+consume time beyond the 3s generation window (overhead/backpressure) · stream overhead (structured): same workload as stream overhead (text), but each delta is an AI-SDK-style structured object ({ type: 'text-delta', id, text }) instead of a raw string, so the SO gap vs the text scenario is the added serialization cost

🔴 marks a percentile over its target (within target is left unmarked). Targets (p75/p90/p99, ms) — TTFS 200/300/600 · SL 50/60/125 · SO 250/500/1000 · STSO (1-20) 20/30/60 · STSO (101-120) 30/45/90 · STSO (1001-1020) 40/60/120

All metrics are measured from deployment-side timestamps only. Runs are triggered by an in-deployment route that stamps the anchor (clientStart) right before start(), so the CI runner’s request and its path through api.vercel.com sit outside every measured window. TTFS = in-deployment start() → first step body (turbo uses the in-process fast path, non-turbo the dispatch path), and includes the VQS dispatch hop plus any /flow cold start. STSO/WO are measured between step bodies on the deployment. SL is measured inside the workflow (parallel reader/writer steps), so it no longer includes the api.vercel.com read path.

Cold starts are kept in the numbers on purpose — they are part of real bursty-workload latency. The workbench deployment cold-starts the /flow invocation for a large fraction of runs, inflating P75+; the Best column shows the fastest (warm-start) sample for comparison.

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