Benchmarks

Measured runtime and product workloads. Each table identifies its binaries, source, measurement method and execution host.

Source: CI run of the aphrody-perf workflow (artifacts perf-report-*).

linux-x64

Fork 1.4.3-aphrody.2 (f7a7086b6) against upstream 1.4.2 (744846f84) on linux 6.17.0-1022-azure x64, AMD EPYC 7763 64-Core Processor x4, 16 GiB; 40 runs, 5 warmup, engine hyperfine, measured 2026-10-09T02:29:50.614Z. Median (p95); ratio = fork / upstream, lower is faster for times.

Measure	Upstream	Fork	Ratio	Gate
`bun --version`	1.40 ms (p95 1.64 ms)	1.54 ms (p95 2.10 ms)	1.098	ok
`bun -e ''`	1.49 ms (p95 1.86 ms)	1.44 ms (p95 1.80 ms)	0.961	ok
`bun run` (empty script)	4.33 ms (p95 5.44 ms)	4.77 ms (p95 6.20 ms)	1.101	ok
`bun test` (one empty test)	4.94 ms (p95 6.69 ms)	5.60 ms (p95 6.70 ms)	1.133	ok
`bun build` (small project)	5.11 ms (p95 6.67 ms)	5.79 ms (p95 7.25 ms)	1.132	ok
`bun install` offline (warm cache)	3.24 ms (p95 3.91 ms)	3.58 ms (p95 4.03 ms)	1.102	ok
RSS at startup	17.3 MiB (p95 17.4 MiB)	32.7 MiB (p95 32.7 MiB)	1.893	info
RSS after loading node:* modules	28.0 MiB (p95 31.2 MiB)	41.5 MiB (p95 44.1 MiB)	1.481	info
`require` of node:* modules	37.5 ms (p95 39.2 ms)	36.1 ms (p95 39.5 ms)	0.963	ok
`import()` of node:* modules	37.6 ms (p95 39.7 ms)	36.5 ms (p95 39.3 ms)	0.970	ok
`require` of bun:* modules	1.31 ms (p95 1.73 ms)	1.38 ms (p95 1.52 ms)	1.053	ok
`Bun.serve` hello + first request	1.64 ms (p95 1.78 ms)	1.73 ms (p95 1.89 ms)	1.054	ok
local `fetch` latency (p50)	0.11 ms (p95 0.13 ms)	0.12 ms (p95 0.14 ms)	1.077	ok
local `fetch` latency (p99)	0.16 ms (p95 0.18 ms)	0.17 ms (p95 0.19 ms)	1.032	info
local `fetch`, sequential throughput	8,485 req/s (p95 9,552 req/s)	8,208 req/s (p95 10,272 req/s)	1.034	info
`require` of fork-only modules (fork only)	n/a	4.23 ms (p95 4.88 ms)		info
Binary size	75.8 MiB	84.8 MiB	1.118	ok

Run note: Release upstream bun-v1.4.3 absente : repli sur bun-v1.4.2. Versions de base différentes (fork 1.4.3-aphrody.2, upstream 1.4.2) : l'écart inclut le travail amont entre les deux; taille et RSS ne bloquent pas (--strict pour les imposer).

windows-x64

Fork 1.4.3-aphrody.2 (f7a7086b6) against upstream 1.4.2 (744846f84) on win32 10.0.26100 x64, AMD EPYC 9V45 96-Core Processor x4, 16 GiB; 40 runs, 5 warmup, engine hyperfine, measured 2026-10-09T02:30:06.789Z. Median (p95); ratio = fork / upstream, lower is faster for times.

Measure	Upstream	Fork	Ratio	Gate
`bun --version`	4.09 ms (p95 4.29 ms)	4.06 ms (p95 4.20 ms)	0.994	ok
`bun -e ''`	4.06 ms (p95 4.20 ms)	4.07 ms (p95 4.43 ms)	1.002	ok
`bun run` (empty script)	10.1 ms (p95 12.3 ms)	11.2 ms (p95 12.0 ms)	1.108	ok
`bun test` (one empty test)	10.6 ms (p95 12.1 ms)	11.6 ms (p95 12.2 ms)	1.089	ok
`bun build` (small project)	8.85 ms (p95 9.37 ms)	9.08 ms (p95 9.34 ms)	1.027	ok
`bun install` offline (warm cache)	26.5 ms (p95 38.2 ms)	19.6 ms (p95 32.3 ms)	0.739	ok
RSS at startup	15.4 MiB (p95 15.4 MiB)	18.5 MiB (p95 18.5 MiB)	1.196	info
RSS after loading node:* modules	23.6 MiB (p95 23.6 MiB)	27.3 MiB (p95 27.3 MiB)	1.155	info
`require` of node:* modules	25.5 ms (p95 26.5 ms)	25.3 ms (p95 26.3 ms)	0.994	ok
`import()` of node:* modules	26.8 ms (p95 31.1 ms)	26.5 ms (p95 34.6 ms)	0.989	ok
`require` of bun:* modules	1.03 ms (p95 1.16 ms)	1.08 ms (p95 1.27 ms)	1.050	ok
`Bun.serve` hello + first request	4.08 ms (p95 4.34 ms)	4.26 ms (p95 4.87 ms)	1.044	ok
local `fetch` latency (p50)	0.03 ms (p95 0.04 ms)	0.03 ms (p95 0.04 ms)	1.015	ok
local `fetch` latency (p99)	0.09 ms (p95 0.17 ms)	0.10 ms (p95 0.24 ms)	1.093	info
local `fetch`, sequential throughput	27,999 req/s (p95 29,901 req/s)	26,055 req/s (p95 27,541 req/s)	1.075	info
`require` of fork-only modules (fork only)	n/a	3.33 ms (p95 3.96 ms)		info
Binary size	82.1 MiB	91.8 MiB	1.118	ok

Run note: Release upstream bun-v1.4.3 absente : repli sur bun-v1.4.2. Versions de base différentes (fork 1.4.3-aphrody.2, upstream 1.4.2) : l'écart inclut le travail amont entre les deux; taille et RSS ne bloquent pas (--strict pour les imposer).

What is measured

bun --version
bun -e ''
bun run (empty script)
bun test (one empty test)
bun build (small project)
bun install offline (warm cache)
RSS at startup
RSS after loading node:* modules
require of node:* modules
import() of node:* modules
require of bun:* modules
Bun.serve hello + first request
local fetch latency (p50)
local fetch latency (p99)
local fetch, sequential throughput
require of fork-only modules (fork only)
Binary size

Thresholds live in bench/aphrody/thresholds.json: a case fails when the runtime median exceeds upstream by more than its ratio and its absolute delta.

Run it yourself

git clone https://github.com/aphrody-labs/bun && cd bun
# runtime binary against the upstream release of the same base version
bun scripts/aphrody/perf-gate.ts --fork ~/.bun/bin/bun --upstream-version 1.4.3 --runs 40 --out tmp/perf

The report is written to tmp/perf/perf-report.md and perf-report.json. The upstream micro-benchmarks of bench/ run with cd bench && bun install && bun run <name>.