A set of rules for keeping websites fast while building or reviewing their front end. It covers loading the first screen, images, vector graphics, animation, and fonts.

Use it when adding images, video, animation, or custom fonts, or when checking a page for loading and interaction slowdowns.

It helps prevent new design or media work from making a page slow, jump during loading, or respond late to input.

How techtankto/techtank-site configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to techtankto/techtank-site. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/techtankto/techtank-site/main/.agents/skills/performance/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/techtankto/techtank-site

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/techtankto/techtank-site/performance/github.svg)](https://agentmods.dev/skills/techtankto/techtank-site/performance)

Your own site

<a href="https://agentmods.dev/skills/techtankto/techtank-site/performance"><img src="https://agentmods.dev/badge/skills/techtankto/techtank-site/performance/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/techtankto/techtank-site/performance"><img src="https://agentmods.dev/badge/skills/techtankto/techtank-site/performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 45 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 221 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original 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.

Model	Per session	Once invoked
Fable 5.1	$0.00045	$0.00221
Opus 5.5	$0.00018	$0.00088
Sonnet 5.5	$0.00009	$0.00044
Haiku 4.5	$0.00005	$0.00022

Measured 2mo ago against content hash 9bb966a22100, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

performance 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 2mo 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.

.agents/skills/performance/SKILL.md · 16 lines

What it actually says

Performance

Fast is a feature; the presentation layer never gets to make the site feel slow.

LCP first. Fast LCP on desktop and mobile; the first screenful renders without layout shift.
Images lazy-load below the fold. Decorative image layers (texture backgrounds, thumbnail walls) never block LCP.
Vector geometry ships as optimized SVG: marks, lines, letterforms, not raster.
The presentation layer has a budget. Entry and loading sequences are capped in duration; motion never blocks interactivity or input.
Motion discipline. Durations, easings, and variants are defined once and imported: no ad-hoc magic numbers per component.
Font loading causes no flash of invisible text and no layout shift on swap.

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.

2mo ago First seen · 16 lines · 45 tokens per session scan A 9bb966a22100

Subscribe to this mod's changes

performance is a skill published in the GitHub repository techtankto/techtank-site (5 stars, last pushed 3d ago), licensed MIT. It adds 45 tokens to every session and 221 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-31.

Frontend

performance next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
performancetechtankto/techtank-site	Skill	5	3d ago	MIT	A	45	Claude Code, Codex
imagegenopenai/codex	Skill	133k	yesterday	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	yesterday	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	4d ago	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	313k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	103	Claude Code

techtank-site: Skill for Claude Code