perf(router-core): classify simple segments before slicing

[Sheraff]

What changed

• classify $param and $ segments from their boundaries before creating a substring
• recognize static segments without allocating their segment substring
• defer substring creation to braced or otherwise complex segment syntax
• add a direct parser benchmark covering mixed, static, deep-static, and braced paths

Why

parseSegment previously allocated a substring before it knew whether the segment needed complex parsing. Simple params, wildcards, and static segments make up the common route grammar, so classifying them from the original path removes avoidable allocation while keeping one canonical parser.

This PR does not require the separate interpolation cleanup. parseSegment is already used by route-tree processing and other core path operations, so the change is independently useful and mergeable in either order.

Impact

Focused local parser benchmarks, each parsing 10,000 complete paths:

• mixed static/parameter path: 1.599 ms to 1.180 ms (about 26.2% faster)
• all-static path: 1.506 ms to 1.338 ms (about 11.2% faster)
• 32-segment all-static path: 9.508 ms to 9.101 ms (about 4.3% faster)
• braced-parameter path: 1.994 ms to 1.781 ms (about 10.7% faster)

react-router.minimal changes from 85,919 to 85,938 bytes gzip (+19 bytes; raw +23 bytes).

Validation

• @tanstack/router-core:test:unit: 105 files / 1,536 tests passed, plus 3 expected failures
• @tanstack/router-core:test:types: TypeScript 5.6 through 7.0 passed
• @tanstack/router-core:test:eslint: zero errors (existing warnings remain)
• focused before/after tests/parseSegment.bench.ts runs
• react-router.minimal bundle-size scenario on main and this branch
• git diff --check

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit b57bc35

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	11m 13s	View ↗
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---

☁️ Nx Cloud last updated this comment at 2026-08-08 12:42:26 UTC

[github-actions]

🚀 Changeset Version Preview

No changeset entries found. Merging this PR will not cause a version bump for any packages.

[github-actions]

Bundle Size Benchmarks

• Commit: 17f8c2bde567
• Measured at: 2026-08-08T12:30:38.002Z
• Baseline source: history:c568caf3f376
• Dashboard: bundle-size history

The following scenarios have bundle-size changes compared with the baseline:

Scenario	Current (gzip)	Delta vs baseline	Initial gzip	Raw	Brotli	Trend
react-router.minimal	83.92 KiB	+19 B (+0.02%)	83.79 KiB	262.63 KiB	72.98 KiB	█████████▁▁▁
react-router.full	87.42 KiB	+19 B (+0.02%)	87.28 KiB	274.35 KiB	76.04 KiB	█████████▁▁▁
solid-router.minimal	33.24 KiB	+19 B (+0.06%)	33.11 KiB	96.48 KiB	29.92 KiB	█████████▁▁▁
solid-router.full	38.06 KiB	+16 B (+0.04%)	37.94 KiB	111.11 KiB	34.26 KiB	█████████▁▁▁
vue-router.minimal	49.51 KiB	+13 B (+0.03%)	49.39 KiB	138.22 KiB	44.67 KiB	█████████▁▁▁
vue-router.full	55.09 KiB	+14 B (+0.02%)	54.96 KiB	156.40 KiB	49.61 KiB	█████████▁▁▁
react-start.minimal	96.68 KiB	+20 B (+0.02%)	96.55 KiB	304.81 KiB	83.74 KiB	█████████▁▁▁
react-start.deferred-hydration	97.40 KiB	+15 B (+0.02%)	96.56 KiB	306.17 KiB	84.48 KiB	█████████▁▁▁
react-start.full	99.85 KiB	+18 B (+0.02%)	99.71 KiB	314.52 KiB	86.44 KiB	█████████▁▁▁
react-start.rsbuild.minimal	100.01 KiB	+14 B (+0.01%)	99.84 KiB	315.35 KiB	86.24 KiB	▁▁▁▆▆▆▆▇▇▇▇█
react-start.rsbuild.minimal-iife	100.42 KiB	+12 B (+0.01%)	100.25 KiB	316.29 KiB	86.52 KiB	▁▁▁▆▆▆▆▇▇▇▇█
react-start.rsbuild.full	103.33 KiB	+15 B (+0.01%)	103.16 KiB	325.44 KiB	89.01 KiB	▁▁▁▅▅▅▅▇▇▇▇█
solid-start.minimal	45.96 KiB	+14 B (+0.03%)	45.83 KiB	137.48 KiB	40.87 KiB	█████████▁▁▁
solid-start.deferred-hydration	49.03 KiB	+21 B (+0.04%)	45.89 KiB	144.94 KiB	43.72 KiB	█████████▁▁▁
solid-start.full	51.04 KiB	+21 B (+0.04%)	50.91 KiB	152.87 KiB	45.15 KiB	█████████▁▁▁
vue-start.minimal	65.50 KiB	+13 B (+0.02%)	65.37 KiB	188.99 KiB	58.31 KiB	█████████▁▁▁
vue-start.full	69.30 KiB	+16 B (+0.02%)	69.17 KiB	201.26 KiB	61.52 KiB	█████████▁▁▁

Current gzip tracks all emitted client JS chunks. Initial gzip tracks only the entry/import graph. Trend sparkline is historical current gzip ending with this PR measurement; lower is better.

[pkg-pr-new]

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commit: b57bc35

[codspeed-hq]

Merging this PR will degrade performance by 20.07%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 5 improved benchmarks
❌ 10 (👁 6) regressed benchmarks
✅ 165 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	ssr dehydrate rich types (solid)	87.3 ms	99.8 ms	-12.54%
❌	Simulation	ssr dehydrate plain control (solid)	119.6 ms	129.3 ms	-7.56%
❌	Simulation	ssr global-mw document (solid)	161.9 ms	169.6 ms	-4.55%
❌	Simulation	client-async-pipeline navigation loop (react)	38.7 ms	39.9 ms	-3.13%
⚡	Memory	mem server error-paths redirect (solid)	588.2 KB	272.8 KB	×2.2
⚡	Memory	mem client preload-churn (vue)	776.2 KB	735.7 KB	+5.5%
⚡	Memory	mem client interrupted-navigations (vue)	499.5 KB	480.6 KB	+3.92%
⚡	Memory	mem client navigation-churn (solid)	570.2 KB	549.8 KB	+3.71%
⚡	Simulation	ssr control-flow unmatched 404 (react)	67.2 ms	65.1 ms	+3.25%
👁	Memory	mem server error-paths not-found (solid)	416.3 KB	793.5 KB	-47.53%
👁	Memory	mem server error-paths not-found (vue)	318.6 KB	2,182.6 KB	-85.4%
👁	Memory	mem server streaming-peak chunked (vue)	11.2 MB	13.5 MB	-17.09%
👁	Memory	mem server error-paths not-found (react)	256.3 KB	266.2 KB	-3.73%
👁	Memory	mem server error-paths unmatched (react)	263.6 KB	602 KB	-56.21%
👁	Memory	mem client unique-location-churn (solid)	341.6 KB	498.5 KB	-31.47%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing agent/parse-segment-branch-order (b57bc35) with main (c568caf)}