benchmark

name	benchmark
description	Use when measuring performance baselines or detecting regressions before and after a change in a Laravel app — page Core Web Vitals, API latency percentiles, build/test velocity, and DB query timing, stored as git-tracked baselines for team comparison.
license	MIT
metadata	{"author":"Petr Král (pekral.cz)"}

Benchmark (Laravel)

Measure real performance baselines for a Laravel app and detect regressions by comparing before/after a change. This skill measures — it produces honest numbers and verdicts. For design guidance on hot paths, defer to @skills/latency-critical-systems/SKILL.md; to act on a regression with an optimization loop, hand off to @skills/benchmark-optimization-loop/SKILL.md.

Constraints

• Apply @rules/sql/optimalize.mdc when reading or interpreting query timing (N+1, index usage, SARGable filters).
• Apply @rules/code-testing/general.mdc if you add or touch any benchmark test (Pest, no describe()).
• Measure, never guess — every number must be a real readback from a running system, command, or tool.
• Control for noise: separate warm vs cold, run repeats (≥5), report median plus p95, fix one variable at a time.
• Same machine, same dataset, same config for before and after — note the environment so a teammate can reproduce.
• Keep secrets and private payloads out of baseline JSON and logs.

Use when

• You need a performance baseline for a page, API route, build step, or query.
• A change (PR, dependency bump, query rewrite, config change) may have caused a regression and you must prove it either way.
• You are comparing two implementations or stack options on the same workload.
• Someone claims "it's faster/slower" without a measured before/after.

Do not use for live design advice (use latency-critical-systems) or for diagnosing one Telescope request (use @skills/laravel-telescope/SKILL.md).

Execution

Pick the modes that match the change. Always record environment first: app URL, commit SHA, APP_ENV, dataset size, cache/opcache state, and whether the run is cold (first hit, caches cleared) or warm (steady state).

Mode A — Page performance (Core Web Vitals)

Measure against the running Laravel app (php artisan serve or the real host).

• Run Lighthouse: npx lighthouse <url> --output=json --output-path=./lh.json --only-categories=performance --chrome-flags="--headless".
• Capture: LCP (target < 2.5s), CLS (< 0.1), INP (< 200ms), FCP (< 1.8s), TTFB (< 0.8s).
• Capture resource weight: total transfer, JS/CSS bytes (post-Vite build), render-blocking resources, request count.
• Run 3–5 times; report median. Lighthouse is noisy — discard the first (cold) run unless cold is the metric you want.

Mode B — API performance (latency percentiles + load)

Target real Laravel routes/controllers. Authenticate as needed; use a realistic payload.

• Quick percentiles: wrk -t4 -c50 -d30s --latency https://app.test/api/orders (reports p50/p90/p99).
• Apache Bench alternative: ab -n 1000 -c 50 https://app.test/api/orders.
• Scripted scenarios (auth, POST bodies, ramp): use k6 (k6 run script.js).
• Capture: p50 / p95 / p99 latency, throughput (req/s), error rate, response size. Warm the route first, then measure.

Mode C — Build / dev velocity

• composer install (cold = no vendor, no cache): time it.
• Asset build: time npm run build (Vite production) and HMR warm-reload feel.
• Test suite: time php artisan test or vendor/bin/pest (note parallel vs serial).
• Static analysis: time vendor/bin/phpstan analyse and time vendor/bin/pint --test.
• Run each at least twice; report cold and warm separately (Composer/PHPStan caches matter).

Mode D — DB query timing

• Identify the hot query via @skills/laravel-telescope/SKILL.md or the slow-query log.
• Run EXPLAIN (or EXPLAIN ANALYZE on MySQL 8) per @rules/sql/optimalize.mdc; record rows examined, key used, and whether a full scan occurs.
• Time the query itself, not the surrounding PHP, to isolate DB cost; cross-check with the Telescope duration for the same request.

Before / After comparison

1. On the base state (before the change), run the relevant modes and write the baseline JSON.
2. Apply the change. Re-run the same modes on the same environment and dataset.
3. Compute the delta and verdict per metric. Re-run any metric whose delta is within run-to-run noise before declaring a regression or win.

Output

Baseline JSON

Store git-tracked, one file per logical target, under tests/Benchmark/ (or .benchmarks/ if you prefer a non-test location). Commit so the team shares one reference.

{
  "target": "GET /api/orders",
  "mode": "api",
  "captured_at": "2026-06-15T10:00:00Z",
  "commit": "abc1234",
  "environment": { "app_env": "local", "dataset": "10k orders", "state": "warm", "runs": 5, "tool": "wrk" },
  "metrics": {
    "p50_ms": 42,
    "p95_ms": 110,
    "p99_ms": 180,
    "throughput_rps": 940,
    "error_rate": 0.0
  }
}

For page mode use keys lcp_ms, cls, inp_ms, fcp_ms, ttfb_ms, js_bytes, transfer_bytes; for build mode seconds per step (cold/warm); for DB mode query_ms, rows_examined, key_used.

Comparison table

Report one row per metric with the delta and an explicit verdict.

Metric	Before	After	Delta	Verdict
p95 (ms)	110	78	-29%	improved
p99 (ms)	180	175	-3%	noise
throughput (rps)	940	1280	+36%	improved
error rate	0.0%	0.4%	+0.4pp	regressed

Verdict legend: improved / regressed / noise (delta within run-to-run variance) / target-miss (still below the target threshold). State the threshold and the noise band you used.

Done when

• Environment is recorded (URL, commit, env, dataset, cold/warm, run count, tool) so the run is reproducible.
• Each in-scope metric has a real measured value from at least the agreed number of repeat runs — never an estimate.
• A git-tracked baseline JSON exists for every measured target.
• For a change review, a before/after comparison table with per-metric delta and verdict is produced, and noise-band deltas are not reported as wins or regressions.
• Any confirmed regression or target-miss is flagged for @skills/benchmark-optimization-loop/SKILL.md or @skills/mysql-problem-solver/SKILL.md as appropriate.