optimize

A guide for finding and fixing slow web interfaces, including problems with loading, drawing updates, animations, images, and the files sent to the browser.

In plain words
What is it for?
Use it to investigate slow page loads, laggy interactions, choppy animations, large images, excessive browser work, network delays, or oversized JavaScript and CSS bundles.
Why use it?
It helps identify what is actually slowing an interface down instead of guessing or optimizing code that does not matter. It also compares performance before and after a change.

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/resciencelab/tryskills/optimize
Any agent
npx skills add ReScienceLab/TrySkills --skill optimize
Clone the repo
git clone --depth 1 https://github.com/ReScienceLab/TrySkills

Made for: Claude Code, Codex.

Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,885 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00052 $0.01885
Opus 5 $0.00026 $0.00942
Sonnet 5 $0.00010 $0.00377
Haiku 4.5 $0.00005 $0.00188

Measured yesterday against content hash 02183edcc94d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

optimize 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 yesterday.

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.

Origin

This is a copy

89% identical to optimize — 10 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/optimize/SKILL.md · 266 lines

How it starts

The opening of the file, as written. The whole thing — 266 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Identify and fix performance issues to create faster, smoother user experiences.

Assess Performance Issues

Understand current performance and identify problems:

  1. Measure current state:

    • Core Web Vitals: LCP, FID/INP, CLS scores
    • Load time: Time to interactive, first contentful paint
    • Bundle size: JavaScript, CSS, image sizes
    • Runtime performance: Frame rate, memory usage, CPU usage
    • Network: Request count, payload sizes, waterfall
  2. Identify bottlenecks:

    • What's slow? (Initial load? Interactions? Animations?)
    • What's causing it? (Large images? Expensive JavaScript? Layout thrashing?)
    • How bad is it? (Perceivable? Annoying? Blocking?)
    • Who's affected? (All users? Mobile only? Slow connections?)

CRITICAL: Measure before and after. Premature optimization wastes time. Optimize what actually matters.

Optimization Strategy

Create systematic improvement plan:

Loading Performance

Optimize Images:

  • Use modern formats (WebP, AVIF)
  • Proper sizing (don't load 3000px image for 300px display)
  • Lazy loading for below-fold images
  • Responsive images (srcset, picture element)
  • Compress images (80-85% quality is usually imperceptible)
  • Use CDN for faster delivery
<img 
  src="hero.webp"
  srcset="hero-400.webp 400w, hero-800.webp 800w, hero-1200.webp 1200w"
  sizes="(max-width: 400px) 400px, (max-width: 800px) 800px, 1200px"
  loading="lazy"
  alt="Hero image"
/>

Reduce JavaScript Bundle:

  • Code splitting (route-based, component-based)
  • Tree shaking (remove unused code)
  • Remove unused dependencies
  • Lazy load non-critical code
  • Use dynamic imports for large components
// Lazy load heavy component
const HeavyChart = lazy(() => import('./HeavyChart'));

Optimize CSS:

  • Remove unused CSS
  • Critical CSS inline, rest async
  • Minimize CSS files
  • Use CSS containment for independent regions

Optimize Fonts:

  • Use font-display: swap or optional
  • Subset fonts (only characters you need)
  • Preload critical fonts
  • Use system fonts when appropriate
  • Limit font weights loaded

Read the full file on GitHub · 266 lines

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. yesterday First seen · 266 lines · 52 tokens per session scan A 02183edcc94d

Subscribe to this mod's changes

optimize is a skill published in the GitHub repository ReScienceLab/TrySkills (2 stars, last pushed 3mo ago), licensed MIT. It adds 52 tokens to every session and 1,885 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to optimize, differing in 10 lines, and is treated as a copy.

Related

Other skills, from other repositories

general-video

Author or edit a custom HyperFrames composition when no specialized workflow fits, or when BRIEF.md sets flow: companion. Use for longer or multi-scene pieces, brand and sizzle reels, montages, static loops, static title cards, footage remixes, and freeform builds. Use motion-graphics instead for a short unnarrated…

heygen-com/hyperframes · 92 tokens

media-ingest

Ingest video, audio, PDF, book, screenshot, and GitHub repo content into the brain. Multi-format handling with entity extraction and backlink propagation. Covers video-ingest, youtube-ingest, and book-ingest subtypes.

garrytan/gbrain · 52 tokens

diagnostic-stem-delivery

Audio production with diagnostic analysis, timecode parsing from documents, and verified export workflow.

HKUDS/OpenSpace · 23 tokens

vox-director

Turn ONE topic into a finished Vox-style paper-collage explainer / ad video, end to end on the Atlas Cloud API + local ffmpeg — script, collage keyframes, motion, voice-over, music, captions, all automated. Use this whenever the user wants a "Vox style" video, a paper/torn-paper collage animation, a "motion collage"…

Alisa0808/vox-director · 236 tokens

seedance-vocab-ja

This skill should be used when the user asks for Japanese Seedance 2.0 prompt wording, Japanese cinematic vocabulary, or translation of camera, lighting, action, VFX, audio, and production terms into Japanese.

Emily2040/seedance-2.0 · 50 tokens

model-compatibility

Model family compatibility matrix covering loaders, resolutions, samplers, CFG, VAE, ControlNet, and LoRA compatibility for SD 1.5, SDXL, Flux, SD3, and video models.

artokun/comfyui-mcp · 47 tokens