Conciseness

The body is dense and assumes Claude's competence — no basic three.js or rendering explanations — with terse, high-value code comments (e.g. 'the counters reset at the start of every render() call'). The Quick Start block includes boilerplate renderer/scene/camera setup that could be trimmed, keeping it below the 'every token earns its place' anchor.

Actionability

Every section provides copy-paste-ready executable code with specific APIs — renderer.info counters, mergeGeometries, InstancedMesh, BatchedMesh, LOD, KTX2Loader, compileAsync, shadow-map freezing, TSL compute — and the examples cover the common optimization cases end to end.

Workflow Clarity

'Measure First' establishes a clear diagnostic sequence, and verification checkpoints appear (checking info.memory after dispose, averaging Timer over 60 frames, separating CPU vs GPU time). A minor gap: there is no explicit counter-to-lever mapping that would guide choosing between sections when a specific number is high.

Progressive Disclosure

The single file is well-sectioned and easily navigable, with clearly signaled one-level See Also links to sibling skills. However, all detail is inlined in a ~390-line file; advanced material such as the WebGPU/TSL compute example or the KTX2 format matrix could be split into reference files.

Specificity

'Measuring and optimizing three.js speed: render statistics, memory counters, fewer draw calls via merging, instancing, batching and LOD, fill rate, shadows, CPU work per frame, shader stalls and GPU compute for particles' lists multiple concrete capabilities covering both measurement and optimization comprehensively, with no vague filler.

Completeness

The 'what' is explicit and enumerated (measure via render statistics and memory counters; optimize via merging, instancing, batching, LOD, fill rate, shadows, CPU work, shader stalls, GPU compute), and the 'when' is an explicit trigger clause: 'Use when a scene is slow, janks or exceeds memory.'

Trigger Term Quality

Natural user phrases are present ('three.js', 'slow', 'janks', 'exceeds memory'), but common synonyms such as 'fps' or 'frame rate' that users would naturally say are missing, matching the 'good keyword coverage; a few natural terms missing' anchor.

Distinctiveness Conflict Risk

The performance niche is clear and the triggers (slow, jank, memory) are distinctly performance-oriented, but listed topics like 'shadows' overlap with closely related sibling skills (threejs-lighting, threejs-geometry), matching the 'minor overlap risk with closely related skills' anchor.