web-performance-optimization

Guidance for making websites and web applications load and run faster. It covers loading speed, Core Web Vitals, bundle size, caching, and runtime performance.

In plain words
What is it for?
Use it to optimize page loads, reduce bundle size, improve Core Web Vitals, configure caching, and tune browser runtime work.
Why use it?
It helps identify delays caused by downloaded code, network caching, or work performed in the browser. Improving these areas can make pages respond sooner.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/dvasyliev/ai-dev-tools-getting-started/web-performance-optimization
Any agent
npx skills add dvasyliev/ai-dev-tools-getting-started --skill web-performance-optimization
Clone the repo
git clone --depth 1 https://github.com/dvasyliev/ai-dev-tools-getting-started

Made for: Claude Code, Codex.

Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,240 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00029 $0.04240
Opus 5 $0.00015 $0.02120
Sonnet 5 $0.00006 $0.00848
Haiku 4.5 $0.00003 $0.00424

Measured 2d ago against content hash 150ac7dd3e69, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

web-performance-optimization scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

antigravity/skills/web-performance-optimization/SKILL.md · 704 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 704 lines · 29 tokens per session scan A 150ac7dd3e69

Subscribe to this mod's changes

web-performance-optimization is a skill published in the GitHub repository dvasyliev/ai-dev-tools-getting-started (21 stars, last pushed 4mo ago), with no licence file. It adds 29 tokens to every session and 4,240 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

vindicate

Use when the user wants to write, add, fix, stabilize (flaky), refactor, run, or audit Playwright browser tests, draft requirements/stories from a recording (no tests), find test-coverage gaps, scaffold a Playwright project, or set up Playwright CI. Vindicate's guided workflow for grounded, conformant Playwright test…

OpenEvident/vindicate · 77 tokens

iblai-api-apply

Platform application gate — turn membership into an apply/review process. Applicant apply/renew/submit flows (drafts, file uploads, fees, withdrawal), reviewer pipeline (list, stats, detail, per-student decisions, notes, waivers, admin override submit, blocks), post-acceptance placement tests and course assignments…

iblai/api · 119 tokens

implement

Implements a feature from its spec following all guardrails: budget, DoD, anti-scope, and pattern compliance. Runs an 8-phase pipeline (find spec → extract guardrails → load patterns → plan → implement → test → refine → self-verify DoD). Use after gen-spec when you're ready to code. The agent has filesystem access and…

pe-menezes/vibeflow · 79 tokens

iblai-api-credential

Manage an ibl.ai organization's digital credentials via the platform API — credential CRUD, user/group assignments, assertions, course-scoped credential import/export, external provider config + mapping (Accredible), and issuance analytics. Use when issuing, assigning, importing, or reporting on digital credentials…

iblai/api · 65 tokens

assistant

Assistant — on any repo, scan README→docs→AGENTS→CONTRIBUTING→PR templates→task runners→devcontainer→CI→configs before code; cite sources; prefer AGENTS.md for agent behavior; portable across Cursor/Copilot/Claude; use agent-toolkit CLI when needed.

ulises-jeremias/agent-toolkit · 64 tokens

design-improvement

WHAT - Browser-grounded iterative design improvement. Consumes design-assessment findings, defines direction, prioritizes safe vs ambiguous changes, implements within existing design system, runs app, captures rendered evidence via browser, reviews and iterates. Reuses evidence model — no new scoring framework.

ulises-jeremias/agent-toolkit · 60 tokens