performance

USE WHEN: Optimizing Core Web Vitals, managing assets, and ensuring high Lighthouse/A11y scores.

Cursor rule for Cursor

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 rules/omergulcicek/omergulcicek.com/performance
Clone the repo
git clone --depth 1 https://github.com/omergulcicek/omergulcicek.com

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 715 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.00715
Opus 5 $0.00000 $0.00358
Sonnet 5 $0.00000 $0.00143
Haiku 4.5 $0.00000 $0.00072

Measured today against content hash 64522fec8805, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 today.

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 · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance & Accessibility (Lighthouse 95+)

Constraints

  • Measurement First: Avoid premature optimization. Identify specific bottlenecks via profiling (DevTools Performance tab) before applying any fixes.
  • Performance Budgets:
    • Core Web Vitals: LCP ≤ 2.5s, INP ≤ 200ms, CLS ≤ 0.1.
    • API & Load: API response time < 200ms (p95). Time to Interactive (TTI) < 3.5s on 4G connections.
    • Bundle Size: Keep initial feature chunks < 50kb. Enforce dynamic imports (next/dynamic) for heavy dependencies.
  • LCP Optimization: Use the priority attribute for the first visible Image (Next.js) or hero assets to prioritize loading.
  • Image & Data Standards:
    • Define explicit width and height to prevent CLS.
    • Use <picture> with source tags for complex art direction or resolution switching.
    • Prevent N+1 query patterns; strictly use pagination or optimized includes/joins for all data-driven components.
  • Icon & Font Strategy: Use tree-shakable icons (e.g., lucide-react). Apply swap display strategy for fonts, optimized via next/font or local self-hosting.
  • A11y SSOT: All interactive elements MUST have aria-label, role, or an associated <label>. Maintain WCAG AA compliance (4.5:1 contrast ratio).
  • Asset Links: Reference ui-components.mdc for specific Skeleton and Layout Shift (CLS) implementation rules.

Bans

  • Layout Shift: Forbidden to render content without reserved dimensions (use Skeletons).
  • Native Img: Forbidden to use raw <img> tags.
  • Blocking JS: Forbidden to use heavy 3rd party scripts in the main thread (use next/script or Web Workers).
  • A11y Gaps: Forbidden to use div as a button without tabIndex and onKeyDown.
  • Alt Text: Forbidden to leave alt attributes empty or generic (e.g., "image").

Correct Implementation

export const Hero = () => (

Read the full file on GitHub · 67 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. today First seen · 67 lines · 0 tokens per session scan A 64522fec8805

Subscribe to this mod's changes

performance is a cursor rule published in the GitHub repository omergulcicek/omergulcicek.com (15 stars, last pushed 6d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 715 tokens. 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 2026-09-01.

Related

Other cursor rules, from other repositories

js-and-ts

When writing JavaScript or TypeScript code, use this guide for JavaScript best practices and guidance.

janhesters/react-router-saas-template · 0 tokens

jsx-and-tsx

When writing React code, use this guide for React best practices and guidance.

janhesters/react-router-saas-template · 0 tokens

facades

When writing facade functions, use this guide for facade functions best practices and guidance.

janhesters/react-router-saas-template · 0 tokens

new-component-implementation

Provides a systematic, research-driven workflow for implementing new Vibe components - for the @vibe/core library (located in "packages/core") - from initial research through final validation. Emphasizes studying existing patterns, following established conventions, and systematic progression through types, component…

mondaycom/vibe · 2,471 tokens

base-components

Comprehensive guide for base components in @vibe/core library (BaseInput, BaseList, BaseListItem, InfoText, FieldLabel). Documents their usage patterns, accessibility requirements, form integration patterns, and what consumers need to provide for optimal accessibility and UX. These components serve as foundational…

mondaycom/vibe · 107 tokens

component-internal-structure

This rule defines conventions for the internal structure of React components within the @vibe/core library (located in "packages/core" directory). Adhering to these conventions ensures consistency, readability, and maintainability across the codebase.

mondaycom/vibe · 1,693 tokens