fix: performance

[lazarv]

Performance optimizations across the SSR hot path: byte-level JS string escaping in render-dom.mjs (eliminates TextEncoder/TextDecoder/JSON.stringify churn), streamlined abort signal handling in middleware.mjs (removes per-request DOMException construction), ESM import caching, response streaming pipeline improvements, and static file handler performance fixes

Benchmark suite with autocannon-based harness, 10 route variants (minimal → large SSR, cached, static files, 404), client component SSR counterparts for RSC vs SSR comparison, --cluster mode support, --save/--compare for A/B testing

GitHub Actions workflow for automated benchmark on PRs and main merges with sticky PR comment showing req/s and latency deltas against baseline

[github-actions]

⚡ Benchmark Results

Commit: 91edc5e | No baseline available (will be created when this PR's target is next pushed to main)

Benchmark	Req/s	Avg Latency	P50	P99	Throughput
minimal	1326	37.16 ms	35 ms	73 ms	0.7 MB/s
small	1469	33.5 ms	33 ms	60 ms	1.3 MB/s
medium	347	143.15 ms	142 ms	216 ms	5.1 MB/s
large	32	1441.63 ms	1433 ms	2650 ms	3.3 MB/s
deep	948	52.11 ms	51 ms	87 ms	3.1 MB/s
wide	44	1113.29 ms	1101 ms	1999 ms	2.4 MB/s
cached	4201	11.38 ms	10 ms	22 ms	61.3 MB/s
client-min	1011	48.78 ms	48 ms	76 ms	2.6 MB/s
client-small	1058	46.7 ms	46 ms	73 ms	3.0 MB/s
client-med	611	80.77 ms	80 ms	120 ms	10.1 MB/s
client-large	95	509.2 ms	509 ms	1019 ms	9.8 MB/s
client-deep	886	55.85 ms	56 ms	81 ms	4.7 MB/s
client-wide	178	277.44 ms	274 ms	475 ms	10.1 MB/s
static-json	8407	5.61 ms	5 ms	14 ms	3.5 MB/s
static-js	7980	5.71 ms	5 ms	15 ms	37.3 MB/s
404-miss	7851	5.7 ms	5 ms	11 ms	1.0 MB/s

Legend

🟢 > 1% improvement | 🔴 > 1% regression | ⚪ within noise margin

Benchmarks run on GitHub Actions runners (shared infrastructure) — expect ~5% variance between runs. Consistent directional changes across multiple routes are more meaningful than any single number.

[codecov-commenter]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
757	1	756	3

View the top 1 failed test(s) by shortest run time

__test__/deno.spec.mjs > preset: get-started-ts

Stack Traces | 300s run time

Error: Hook timed out in 300000ms.
If this is a long-running hook, pass a timeout value as the last argument or configure it globally with "hookTimeout".
 ❯ __test__/deno.spec.mjs:46:18

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