Conciseness

Largely token-efficient — symptom→cause tables, a symptom decision tree, and numeric budgets carry the content, and worked fixes are pushed to the reference file. Minor over-explanation remains in Step 4's motivational prose ("This is the step teams skip: the change is already written, throwing it away feels wasteful...") and in Common Rationalizations rows that restate Step 3 bullets ("The query is slow, add an index", "Just cache it"). Not 5 because a few passages could be trimmed without losing guidance; not 3 because the padding is minor relative to the dense signal.

Actionability

Mostly executable — copy-paste `import { onLCP, onINP, onCLS } from 'web-vitals'`, `npx bundlesize --config bundlesize.config.json`, `npx lhci autorun`, concrete `EXPLAIN ANALYZE` plan-reading guidance, numeric budgets, and a strict keep/revert decision table. Not 5: the backend Step 1 block is comment placeholders ("Response time logging / Application Performance Monitoring (APM)") with no runnable command, and some Step 3 entries are rules rather than examples. Anchor 4 (concrete code with minor gaps) is the best fit.

Workflow Clarity

Clear five-step sequence (MEASURE → IDENTIFY → FIX → VERIFY → GUARD) with explicit validation: "Re-measure the way you measured the baseline: same command, same conditions, same fixed budget", a keep-or-revert decision table gated on tests staying green, a feedback loop ("When either guard fires, return to Step 1 and establish a fresh baseline"), and a 13-item verification checklist. Direct match to anchor 5 (explicit validation, feedback loops, checklist).

Progressive Disclosure

SKILL.md keeps worked fixes in a well-signaled, one-level-deep reference file ("links to a worked fix in references/optimization-patterns.md... Open the one you need when you reach that code, not before"), and all 8 anchored links (n1-queries-backend, unbounded-data-fetching, queries-that-ignore-their-index, connection-pool-exhaustion, missing-caching-backend, missing-image-optimization-frontend, unnecessary-re-renders-react, large-bundle-size) resolve to real sections in the bundle. Not 5 because `../../references/performance-checklist.md` is referenced twice (Step 3 caching entry and the See Also section) yet is absent from the bundle — a dangling navigation target that leaves the skill directory.

Specificity

The what-clause — "Optimizes application performance across frontend, backend, queries, and databases" — names the domain and a single action. Concrete actions appear only inside the when-clause ("N+1 query patterns need fixing"), so it matches anchor 3 (domain plus 1-2 concrete actions, not comprehensive) rather than anchor 4, which requires several specific listed actions such as "profiles bottlenecks, fixes N+1 queries, reduces bundle size".

Completeness

Explicitly answers both: what ("Optimizes application performance across frontend, backend, queries, and databases") and when, via an explicit "Use when..." clause with four concrete triggers ("when performance requirements exist", "when you suspect performance regressions", "when Core Web Vitals or load times need improvement", "when N+1 query patterns need fixing, or when profiling reveals bottlenecks"). Matches anchor 5; the when-clause is more explicit than anchor 4's example, so 4 would understate it.

Trigger Term Quality

Good coverage of natural terms users would say: "performance regressions", "Core Web Vitals", "load times", "N+1 query patterns", "profiling", "bottlenecks". Common variations like "slow", "latency", "response times", or "speed up" are absent, so anchor 4 (good coverage, a few natural terms missing) fits better than anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

A clear performance-tuning niche with distinctive triggers (Core Web Vitals, N+1 query patterns, profiling, bottlenecks) unlikely to fire for unrelated skills, and correct third-person voice ("Optimizes") with no first/second-person penalty. Anchor 5 (clear niche, minimal conflict risk) is the best fit; adjacent skills like a generic database skill would not claim these triggers.