name: audit-performance-frontend description: Low-level frontend performance audit, specialized for WebKit/JSC and embedded or real-time contexts - on a mainstream stack (React/Chrome SPA) many questions are N/A and the grid adapts. Use when auditing frontend rendering performance, WebKit internals, JSC optimization, DOM structure, CSS rendering pipeline, memory/GC, cache strategy, or profiling methodology. Triggers on "audit performance", "audit frontend", "audit perf", "audit rendering", "audit webkit", "audit jsc". version: 1.0.2 metadata: last-reviewed: 2026-07-20 category: audit

When ME and not audit-industrialisation

• ME when: an audit scoped to this domain only
• audit-industrialisation instead if: a cross-domain global audit - it orchestrates every audit (including ME) and produces a consolidated report

For a full project audit, use audit-industrialisation rather than invoking each skill separately.

Low-Level Frontend Performance Audit

Scope check before starting: this grid targets WebKit/JSC internals and

embedded/real-time constraints. On a mainstream stack (e.g. a React SPA on

evergreen browsers), mark the engine-specific questions N/A per the Variants

section instead of forcing answers - a mostly-N/A domain is a valid outcome.

Overview

Audit a project's frontend performance maturity, targeting sub-100ms rendering. Covers the integrity of the rendering pipeline: DOM structure, CSS rendering, JS engine internals (JSC), memory and GC management, network/cache strategy, and profiling tooling. Micro-optimization oriented, for embedded or real-time contexts running on WebKit.

29 questions split across 6 categories:

Scoring

• Each scored question gets a level from 0 to 4.
• Questions marked N/A are excluded from the calculation.
• Domain score = sum of levels / number of scored questions (excluding N/A).
• Criticality (used to prioritize remediation, NOT in the score - see audit-report/reference/scoring-model.md):
• MUST: PF-01, PF-02, PF-03, PF-06, PF-10, PF-13, PF-17, PF-23, PF-27, PF-28, PF-29
• SHOULD: PF-04, PF-05, PF-07, PF-09, PF-11, PF-12, PF-14, PF-15, PF-19, PF-20, PF-21, PF-22, PF-24, PF-25, PF-26
• COULD: PF-08, PF-16, PF-18

Audit protocol

1. Detect the project type: SPA, SSR, PWA, embedded WebKit, component library.
2. Category 1 - HTML: scan for document.write, measure DOM depth, check blocking scripts and priority attributes.
3. Category 2 - CSS: audit selectors, animations, compositing, custom properties, fonts.
4. Category 3 - JS Engine: look for polymorphism patterns, delete, arrow functions in loops, eval, sparse arrays.
5. Category 4 - Memory: check allocations in loops, event listeners without cleanup, caches without eviction.
6. Category 5 - Assets: measure critical-path size, check compression, cache headers, font loading.
7. Category 6 - Profiling: check instrumentation, metrics, performance CI.
8. Run the verification commands for each question (see grids).
9. Assign a level (0-4) per question with justification and confidence level.
10. Mark N/A the non-applicable questions (e.g. PF-10 to PF-18 if there is no custom JS, just a framework).
11. Produce the report (output format below).

Variants by project type

SSR application (Nuxt, Next.js)

• PF-01 to PF-04: Fully applicable, the server generates the initial HTML
• PF-23: Adapted - TTFB includes server render time

UI component library

• PF-23 to PF-26: N/A (no control over deployment)
• PF-27 to PF-29: Adapted - component performance benchmarks

Static site (11ty, Hugo, Astro)

• PF-10 to PF-18: Often N/A (little custom JS)
• PF-01 to PF-09, PF-23 to PF-29: Fully applicable

Embedded WebKit application (WKWebView, Electron)

• Every question applies with the standard grid
• Particular focus on PF-10 to PF-22 (memory/CPU constraints)

Grids by category

Each grid contains, per question: statement, criticality, elements to analyze, bash verification commands, points to check, and a 0-4 level table.

• reference/html-critical-path.md - Category 1, HTML & Critical Path, 4 questions (PF-01 to PF-04)
• reference/css-rendering-pipeline.md - Category 2, CSS & Rendering Pipeline, 5 questions (PF-05 to PF-09)
• reference/js-engine-runtime.md - Category 3, JavaScript Engine & Runtime JSC, 9 questions (PF-10 to PF-18)
• reference/memory-gc.md - Category 4, Memory & Garbage Collection, 4 questions (PF-19 to PF-22)
• reference/assets-cache-network.md - Category 5, Assets, Cache & Network, 4 questions (PF-23 to PF-26)
• reference/profiling-tooling.md - Category 6, Profiling & Tooling, 3 questions (PF-27 to PF-29)

Output format

## Frontend Performance - Global score: X.X/4 (Y questions scored out of 29)
 
### Summary
[2-3 sentences summarizing frontend performance maturity]
[Detected project type: SPA / SSR / PWA / embedded / static]
 
### Detail by question
 
#### Category 1 - HTML & Critical Path
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-01 | DOM structure and parsing | MUST | X | high/medium/low | ... |
| PF-02 | Render-blocking | MUST | X | high/medium/low | ... |
| PF-03 | Layout thrashing | MUST | X | high/medium/low | ... |
| PF-04 | Loading & priority | SHOULD | X | high/medium/low | ... |
 
#### Category 2 - CSS & Rendering Pipeline
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-05 | CSS selectors | SHOULD | X | high/medium/low | ... |
| PF-06 | Layout triggers | MUST | X | high/medium/low | ... |
| PF-07 | Paint & GPU | SHOULD | X | high/medium/low | ... |
| PF-08 | Custom properties | COULD | X | high/medium/low | ... |
| PF-09 | Font rendering | SHOULD | X | high/medium/low | ... |
 
#### Category 3 - JavaScript Engine & Runtime
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-10 | JSC monomorphism | MUST | X | high/medium/low | ... |
| PF-11 | NaN-boxing | SHOULD | X | high/medium/low | ... |
| PF-12 | JSC compilation tiers | SHOULD | X | high/medium/low | ... |
| PF-13 | Deoptimization | MUST | X | high/medium/low | ... |
| PF-14 | Functions & closures | SHOULD | X | high/medium/low | ... |
| PF-15 | JSC arrays | SHOULD | X | high/medium/low | ... |
| PF-16 | Strings & RegExp | COULD | X | high/medium/low | ... |
| PF-17 | Event loop | MUST | X | high/medium/low | ... |
| PF-18 | Weak references | COULD | X | high/medium/low | ... |
 
#### Category 4 - Memory & GC
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-19 | GC Riptide | SHOULD | X | high/medium/low | ... |
| PF-20 | Allocation pressure | SHOULD | X | high/medium/low | ... |
| PF-21 | Memory leaks | SHOULD | X | high/medium/low | ... |
| PF-22 | GPU memory | SHOULD | X | high/medium/low | ... |
 
#### Category 5 - Assets, Cache & Network
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-23 | Network critical path | MUST | X | high/medium/low | ... |
| PF-24 | Compression & encoding | SHOULD | X | high/medium/low | ... |
| PF-25 | Multi-layer cache | SHOULD | X | high/medium/low | ... |
| PF-26 | Font loading | SHOULD | X | high/medium/low | ... |
 
#### Category 6 - Profiling & Tooling
 
| Code | Question | Criticality | Level | Confidence | Justification |
|------|----------|-----------|--------|-----------|---------------|
| PF-27 | Methodical profiling | MUST | X | high/medium/low | ... |
| PF-28 | Sub-100ms metrics | MUST | X | high/medium/low | ... |
| PF-29 | Performance regression CI | MUST | X | high/medium/low | ... |
 
### Strengths
-...
 
### Weaknesses
-...
 
### Recommendations
1.[MUST] ...
2.[SHOULD] ...
3.[COULD] ...
 
### Non-auditable items
-[List the items impossible to verify by static analysis: runtime metrics, JIT profiling, real GC pauses, real-world VRAM, etc.]

Exit condition

• [ ] Project type detected and matching variant applied
• [ ] All 29 questions reviewed (scored 0-4 or marked N/A with justification)
• [ ] Verification commands run for each scored question
• [ ] Confidence level assigned per question
• [ ] Global score computed (excluding N/A)
• [ ] Report produced in the output format, with strengths/weaknesses, prioritized recommendations, and non-auditable items

Changelog

• 1.0.2 (2026-07-20) - scope made explicit (WebKit/JSC specialization; mainstream stacks expect many N/A)

• 1.0.1 (2026-07-20) - scoring aligned with scoring-model.md: flat mean only; criticality kept for remediation priority, weights removed from the score

• 1.0.0 (2026-06-19) - initial versioned release + state-of-the-art enrichment (routing, context, protocol, traps, exit condition); audit grids in reference/ (progressive disclosure)