performance

performance is a cursor rule for Cursor from kok-o/koko-contextos-agents. It costs 5 tokens per session (942 once invoked), scanned A, original, MIT.

A set of web-performance rules for keeping pages fast and meeting Core Web Vitals, which are Google's measures of loading speed, responsiveness, and visual stability.

In plain words
What is it for?
Analyzing or improving page loading, network requests, JavaScript bundles, animations, image and video layout, and data caching.
Why use it?
It helps prevent slow requests, oversized imports, layout shifts, and other changes that make websites feel sluggish or unstable.

Cursor rule for Cursor

Written for Cursor: installed under .cursor/.

Good fit Analyzing or improving page loading, network requests, JavaScript bundles, animations, image and video layout, and data caching.

Compare 6 cursor rules from other repositories ↓
Install with agentmods
npx agentmods add rules/kok-o/koko-contextos-agents/performance
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.

Clone the repo
git clone --depth 1 https://github.com/kok-o/koko-contextos-agents

Made for: Cursor.

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.

agentmods badge for performance

README.md
[![agentmods](https://agentmods.dev/badge/rules/kok-o/koko-contextos-agents/performance/github.svg)](https://agentmods.dev/rules/kok-o/koko-contextos-agents/performance)
Your own site
<a href="https://agentmods.dev/rules/kok-o/koko-contextos-agents/performance"><img src="https://agentmods.dev/badge/rules/kok-o/koko-contextos-agents/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.

agentmods 80×15 button for performance

Your own site · 80×15
<a href="https://agentmods.dev/rules/kok-o/koko-contextos-agents/performance"><img src="https://agentmods.dev/badge/rules/kok-o/koko-contextos-agents/performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 5 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 942 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00005 $0.00942
Opus 5.5 $0.00002 $0.00377
Sonnet 5.5 $0.00001 $0.00188
Haiku 4.5 $0.00001 $0.00094

Measured 1mo ago against content hash c3c139547bcd, 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 1mo 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.

.cursor/rules/performance.mdc · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: Web Performance

Web Performance & Core Web Vitals

Overview

Enforces high-efficiency frontend and full-stack performance standards to achieve exceptional Core Web Vitals: Largest Contentful Paint (LCP < 2.5s), Interaction to Next Paint (INP < 200ms), and Cumulative Layout Shift (CLS < 0.1).

When to Use

Activate whenever analyzing, profiling, writing, or optimizing page loading speeds, network waterfalls, script bundling, animation frame rates, or data caching.

Negative Constraints (What NOT to Do)

  1. NEVER introduce async waterfalls: Do not chain sequential await calls when requests can be executed concurrently via Promise.all().
  2. NEVER import large full libraries when only a utility is needed: Never import _ from 'lodash'; use import debounce from 'lodash/debounce' or native alternatives.
  3. NEVER render images or videos without explicit aspect ratios: Always provide width and height or aspect-ratio to avoid Cumulative Layout Shift (CLS).
  4. NEVER trigger synchronous layout thrashing: Do not alternate between reading layout properties (offsetHeight, getBoundingClientRect) and writing styles in loops.
  5. NEVER animate non-composited properties: Animate only GPU-composited CSS properties (transform, opacity). Never animate width, height, top, left, or margin.

Rules & Patterns

1. Vercel Optimization Hierarchy by Impact

Priority Category Key Optimization Target Expected Impact
1. CRITICAL Eliminating Waterfalls Parallel data fetching (Promise.all), Suspense streaming 30–60% faster LCP
2. CRITICAL Bundle Size Optimization Direct submodule imports, next/dynamic, deferring 3rd party scripts 40–70% smaller initial JS
3. HIGH Server-Side & RSC Caching React.cache() request deduplication, edge SSR caching Lower TTFB & DB load
4. MEDIUM-HIGH Client Query Optimization SWR / TanStack Query stale-while-revalidate, deduplication Zero redundant network calls
5. MEDIUM Render & DOM Optimization Virtualization for large lists, state colocation, :focus-visible Smooth 60 FPS / INP < 100ms

Read the full file on GitHub · 79 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. 1mo ago First seen · 79 lines · 5 tokens per session scan A c3c139547bcd

Subscribe to this mod's changes

performance is a cursor rule published in the GitHub repository kok-o/koko-contextos-agents (2 stars, last pushed 1mo ago), licensed MIT. It adds 5 tokens to every session and 942 once invoked, about $0.0000 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.

Related

Other cursor rules, from other repositories

deepen-architecture

Find deepening opportunities in a codebase, informed by the domain language in specs/tech-architecture/tech-stack.md and the decisions in specs/adr/. Use when the user wants to improve architecture, find refactoring opportunities, consolidate tightly-coupled modules, or make a codebase more testable and AI-navigable.

danielvm-git/bigpowers · 67 tokens

craft-skill

Create new bigpowers skills with proper structure, progressive disclosure, and bundled resources. Use when user wants to create, write, or build a new skill for the bigpowers lifecycle.

danielvm-git/bigpowers · 36 tokens

grill-me

Interactive assumption-surfacing Q&A that stress-tests a plan through relentless questioning until every decision is resolved. Use when user wants to challenge a plan, validate decisions from conversation/context, or mentions "grill me". For doc-grounded variant, use grill-with-docs.

danielvm-git/bigpowers · 55 tokens

run-planning

DISCOVER-PHASE ADVANCER — Drive the discover-phase checklist (specs/planning-status.yaml) through survey-context → scope-work → research-first → elaborate-spec → plan-release → slice-tasks. NOT a duplicate of plan-work or the planning spine; it orchestrates the pre-coding discover phase only.

danielvm-git/bigpowers · 64 tokens

slice-tasks

PLANNING SPINE STEP 2 of 3 — Slice the work: break a scoped PRD into vertical-slice stories in specs/epics/. Use after scope-work (step 1), before plan-work (step 3). Not a substitute for scope-work or plan-work.

danielvm-git/bigpowers · 59 tokens

terse-mode

Fallback ultra-compressed communication mode. Cuts token usage 75% by dropping filler, articles, and pleasantries while keeping full technical accuracy. Use ONLY when context is critically long and compressing output is necessary to continue. Not a strategy — token discipline comes from code shape (small functions…

danielvm-git/bigpowers · 101 tokens