# Performance Estimation

> Use Jeff Dean and Sanjay Ghemawat's canonical estimation guidance for back-of-the-envelope performance calculations. Use when comparing designs before implementation, estimating latency or resource cost, reasoning about operation counts, or deciding what is likely to dominate.

- Skill: `boshjerns/performance-estimation` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add boshjerns/performance-estimation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/boshjerns/performance-estimation/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: boshjerns (https://skillmd.com/u/boshjerns)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/boshjerns/performance-estimation

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# Estimation

Read the exact current source section before applying it:

```bash
python3 ~/.codex/skills/performance-hints/scripts/fetch_section.py estimation --output text
```

Canonical section: [Estimation](https://abseil.io/fast/hints#estimation)

Attribute the guidance to Jeff Dean and Sanjay Ghemawat. Do not assume every hint applies: inspect the code, identify the relevant cost, and measure or estimate before recommending a change.

This section includes:
- Example: Time to quicksort a billion 4 byte numbers
- Example: Time to generate a web page with 30 image thumbnails