Conciseness

The body runs ~495 lines and, while much of it is non-obvious judgment (EXPLAIN ANALYZE interpretation, pool sizing, cache stampede handling), several sections re-teach fundamentals Claude already knows: React.memo/useMemo basics, route-level code splitting, a full 50-line <picture> element example, and a hand-rolled TTL cache. This matches the 3 anchor (mostly efficient with some unnecessary explanation); it is not 4 because the padding is more than minor and not 2 because the majority of sections do earn their tokens.

Actionability

Extensive concrete guidance: executable SQL (EXPLAIN ANALYZE, CREATE INDEX), TypeScript fixes, symptom→cause→investigation tables, a symptom decision tree, and CI commands (npx bundlesize, npx lhci autorun). Minor gaps keep it below the 5 anchor: the synthetic-measurement bash block is comments only, `db.query(...)` and the `res.set` fragment are illustrative rather than copy-paste ready, and bundlesize.config.json is referenced but not shown.

Workflow Clarity

The MEASURE→IDENTIFY→FIX→VERIFY→GUARD workflow is explicitly sequenced with a dedicated validation step: re-measure under identical conditions, compare deltas against noise, a strict keep/revert decision table, correctness gates, a reverted-attempt ledger, and a final checklist. Feedback loops are present (revert on neutral/worse, return to Step 1 when a guard fires), matching the 5 anchor.

Progressive Disclosure

Section structure and headers are good, but the body is a ~495-line monolith with deep detail (the full picture-element markup, the complete anti-pattern fix catalog) inlined that belongs in a separate reference file, and the only external pointer — `../../references/performance-checklist.md`, cited twice — does not exist anywhere in the bundle (no references/ directory). This matches the 3 anchor (content that should be separate is inline; references not backed by real files); it is not 2 because navigation within the body itself is well organized.

Specificity

The description names four concrete domains ("frontend, backend, queries, and databases") and specific patterns ("N+1 query patterns", "Core Web Vitals"), but the capability side rests on a single generic verb ("Optimizes"), so it sits between the 3 anchor (1-2 concrete actions) and the 5 anchor (multiple specific actions) — noticeably above the midpoint. Not 5 because it never states distinct actions like profile, fix, or re-measure.

Completeness

Clearly answers both: what it does ("Optimizes application performance across frontend, backend, queries, and databases") and when to use it via an explicit five-clause "Use when..." with concrete trigger phrases. This matches the 5 anchor exactly; the 4 anchor would require a less explicit 'when', which is not the case.

Trigger Term Quality

Strong natural phrases users would say: "performance requirements", "performance regressions", "Core Web Vitals", "load times", "N+1 query patterns", "profiling reveals bottlenecks". Missing common synonyms such as "slow", "latency", "speed up", or "throttling", which keeps it below the 5 anchor's comprehensive synonym coverage.

Distinctiveness Conflict Risk

Performance optimization is a clear niche and the triggers (Core Web Vitals, N+1 queries, profiling bottlenecks) are distinctive to it, giving minimal conflict risk. The 4 anchor's "minor overlap risk" would apply if it shared triggers with closely related skills (e.g., a dedicated database-tuning skill), but the stated scope explicitly claims those areas as performance work.