Rari vs Next.js: Engineering Benchmark

Instrument both frameworks with OpenTelemetry spans, benchmark with wrk, and visualize timelines in Jaeger to verify Rari's claimed 18x speedup.

TL;DR: Rari is faster. 59x on static prerender, 3.4x on streaming Suspense. 18x is a conservative estimate for uncached dynamic scenarios.

Quick Start

docker compose build jaeger wrk
docker compose up -d jaeger rari-app next-app
docker compose run --rm wrk

• Rari: http://localhost:3001
• Next.js: http://localhost:3002
• Jaeger: http://localhost:16686

Benchmark Scenarios

Route	Rari	Next.js	What it measures
/	cache warmup (pre-render)	static prerender	HTTP serving speed
/stream	loading.tsx + no-cache	force-dynamic + Suspense	Progressive streaming

Streaming route: 10 <Suspense> boundaries with delays 100ms×5, 500ms×3, 1000ms×2.

Results

Static (both prerender)

Metric	Rari	Next.js	Ratio
req/s	131,987	2,228	59x
p50 latency	0.62ms	42ms	68x
throughput	474 MB/s	18.6 MB/s	25x

Streaming Suspense (both dynamic)

Metric	Rari	Next.js	Ratio
req/s	74	22	3.4x
TTFB	7ms	5ms	0.7x
Chunks	13	14	—
Inter-chunk gap p95	500ms	500ms	identical

Directory Layout

Directory	Description
rari/	Fork of rari-build/rari — patched with OTel spans
nextjs/	Fork of vercel/next.js — patched with OTel spans
app/rari-hello/	Rari test app with RSC component tree
app/next-hello/	Next.js test app with identical RSC tree
wrk/	wrk scripts + stream-profile.js (per-chunk profiler)
otel/	OpenTelemetry Collector config
docs/	Article, specs, plans
results/	Benchmark results

OTel Pipeline

Both apps export traces directly to Jaeger via OTLP HTTP:

Rari (tracing crate) → tracing-opentelemetry bridge → Jaeger (:4318)
Next.js (instrumentation.ts) → OTLPTraceExporter → Jaeger (:4318)

Rari span points (Rust)

http.request, handle_app_route, route.match, v8.execute_script, v8.execute_composition, v8.execute_script_streaming, rsc.render, rsc.serialize, rsc.serialize_json

Next.js span points (TypeScript)

Built-in: BaseServer.handleRequest, AppRender.componentTree, AppRender.renderToReadableStream, AppRender.rscPayload

Patched: AppRender.jsonStringifyBootstrap, AppRender.jsonStringifyData

Docker Build Notes

Building Rari with embedded V8 + Deno takes ~60 min on first run. Optimizations:

• Phased COPY in Dockerfile: manifests first (cache deps), source code second (cache .rs files)
• --mount=type=cache for cargo registry, git db, .rusty_v8, target/
• Incremental rebuild after .rs changes: ~3 min

Reproducibility

# Full cycle
docker compose build
docker compose up -d jaeger rari-app next-app
docker compose run --rm wrk

# Streaming profiler only
docker compose run --rm wrk sh -c "node /wrk/stream-profile.js rari-app:3000 next-app:3000"

Results land in results/.