swiftperf Swift performance guide (v0)swiftperf rule ids (slugs)swiftperf corpus targets swiftperf evidence policy

sp-array-no-reserve — measured, still hint sp-clock-hot — measured, still hint sp-dateformatter-hot — measured, still hint sp-file-read-hot — measured, still hint sp-json-decode-hot — measured, still hint sp-print-hot — measured, stays off sp-regex-hot — measured, still hint sp-value-for-key-hot — measured, still hint

sp-clock-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-dateformatter-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-file-read-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-force-unwrap-in-loop — blocked sp-force-unwrap-in-loop — removed 2026-10-23 (Asia/Shanghai)sp-json-decode-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-map-joined-chain — blocked sp-map-joined-chain — removed 2026-10-23 (Asia/Shanghai)sp-print-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-regex-in-loop — renamed 2026-10-27 (Asia/Shanghai)sp-string-plus-in-loop — blocked sp-string-plus-in-loop — removed 2026-10-23 (Asia/Shanghai)sp-value-for-key-in-loop — renamed 2026-10-27 (Asia/Shanghai)

Project

Contributing Changelog Security Policy Contributor Covenant Code of Conduct AGENT.md — XPerf agent operating contract

LanguagesSwiftEvidence_removed

sp-string-plus-in-loop — removed 2026-10-23 (Asia/Shanghai)

Status: removed. swiftc -O, Apple Swift 6.3.2. A 50000-character += was slower after reserveCapacity (0.585 ms versus 1.117 ms). Thirty-two-character builders repeated 2000 times were also slower with reserve (0.646 ms versus 1.410 ms). Checksums matched. No matcher.

Slug never reused.
The old blocked note stays beside this file. Fixtures are under _removed/fixtures/.

sp-string-plus-in-loop — blocked

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sp-value-for-key-in-loop — renamed 2026-10-27 (Asia/Shanghai)

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