# performance

This skill measures Flows performance, tracks down unnecessary renders and costly data requests, then checks the changes against a baseline. Use it when the UI feels slow or handles large query results.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1900 installs · ★ 6
- Author: cognitedata
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/cognitedata/builder-skills/tree/HEAD/skills/performance/SKILL.md
- Updated: 2026-10-20
- HTML: https://affpapa.org/en/nevibecode/skills/cognitedata-performance

## What it does

The skill starts by capturing production-build metrics, a Lighthouse audit, and React Profiler data. It then looks for avoidable renders and suggests memoizing values or handlers when the Profiler confirms a problem. `React.memo` is reserved for presentational components that actually rerender unnecessarily. Measure before and after; otherwise, you cannot tell whether a change helped.

It also inspects DMS access and result handling. For filtered reads, it recommends `instances.query`; for full-text lookup, `instances.search`. Filters and limits move into the API request instead of running over a large array in the browser. The guidance keeps `instances.list` for writes and syncing, so replacing every call would be the wrong fix.

A separate check looks for chat completions applied to DMS rows. The suggested alternative is one agent message; if per-item calls remain, the described limits are 5 and 50, with caching and user-triggered execution. Build examples use `pnpm`.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add cognitedata/builder-skills --skill performance -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/performance/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/performance/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add cognitedata/builder-skills --skill performance -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/performance/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add cognitedata/builder-skills --skill performance -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/performance/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install cognitedata/builder-skills performance
```

2. **Manually: put the files in place**
- File: `.github/skills/performance/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add cognitedata/builder-skills --skill performance -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/cognitedata/builder-skills --path skills/performance
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/performance/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add cognitedata/builder-skills --skill performance -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/cognitedata/builder-skills/tree/HEAD/skills/performance/SKILL.md

## When to use it
- trace components that render unnecessarily
- switch read-heavy DMS calls to filtered queries
- move browser-side filtering into API requests
- reduce chat-model calls across DMS rows
- compare performance measurements before and after a fix

## Example prompts
- Measure the Flows app before and after checking `src/components/AssetTable.tsx` for unnecessary renders.
- Find read-heavy DMS uses of `instances.list` and move supported filters into API requests.
- Check whether chat completions run once per DMS row, then suggest a safer pattern and measure the result.

## Source text · SKILL.md · Apache-2.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: a5377afdc7a46a69.

BEGIN THIRD-PARTY FILE a5377afdc7a46a69
````text
---
name: performance
description: "MUST be used when fixing Flows app performance — re-renders, query patterns, pagination, unbounded fetches, LLM-over-query-results, bundles, memory leaks. Measure before and after. Triggers: performance, slow, laggy, optimize, re-render, bundle size, CDF query, virtualize, chat completions, LLM cost."
allowed-tools: Read, Glob, Grep, Shell, Write
metadata:
  argument-hint: "[file, component, or area to optimize — e.g. 'src/components/AssetTable.tsx']"
---

# Performance Fix

Systematically find and fix performance issues in **$ARGUMENTS** (or the whole app if no argument is given). Always measure first — never optimize blindly.

---

## Step 1 — Measure baseline before touching anything

Run the production build and capture metrics before making any changes:

```bash
pnpm run build
pnpm run preview
```

Open the app in Chrome and capture:
- **Lighthouse score** (Performance tab → Run audit)
- **React Profiler** (React DevTools → Profiler → Record an interaction)
  - Note the components with the longest render times and highest render counts

Record baseline numbers. Every fix must be measured against these.

---

## Step 2 — Find and fix unnecessary re-renders

Read the component tree (start from `src/App.tsx`) and search for these patterns:

```bash
grep -rn --include="*.tsx" \
  -E "value=\{\{|onClick=\{\(\)" src/
```

For each instance found, **apply the fix directly**:

**Inline object/array creation in JSX → wrap with `useMemo`:**
```tsx
// BAD — new object on every render causes children to re-render
<Chart options={{ color: "red" }} />

// FIX — wrap with useMemo
const chartOptions = useMemo(() => ({ color: "red" }), []);
<Chart options={chartOptions} />
```

**Event handlers recreated on every render → wrap with `useCallback`:**
```tsx
// BAD
<Button onClick={() => doSomething(id)} />

// FIX — wrap with useCallback
const handleClick = useCallback(() => doSomething(id), [id]);
<Button onClick={handleClick} />
```

**Context that changes on every render → memoize the context value:**
```tsx
// BAD — new object reference every render
<MyContext.Provider value={{ user, sdk }}>

// FIX — memoize the context value
const ctxValue = useMemo(() => ({ user, sdk }), [user, sdk]);
<MyContext.Provider value={ctxValue}>
```

Apply `React.memo` to pure presentational components that receive stable props. Do NOT wrap every component — only those confirmed to re-render unnecessarily via the Profiler.

---

## Step 3 — Find and fix DMS query patterns
````
END THIRD-PARTY FILE a5377afdc7a46a69

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