How do I install the Profile skill?

Run npx skillmds@latest add ccusage/profile in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Profile skill do?

Profiles ccusage performance. Use when a CLI command is slow, when checking that an optimization actually helped, when comparing a branch against main, or when reading a captured CPU profile. It is listed under Coding & Dev Tools on SkillMD.

Is Profile safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Profile?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Profile free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Profile?

ccusage (@ccusage) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Profile by ccusage — Agent Skill

Name: Profile
Author: ccusage

File contents

ccusage Profile

Nearly all runtime cost lives in the Rust binary. references/rust.md covers release builds, the branch-vs-main worktree setup, deterministic measurement, JSON parity, and reproducing the CI performance comment.

Two habits carry across every profiling session here:

Measure end-to-end on real logs before trusting a profile. The wins in this repository came from timing the real CLI over real Claude data; a microbenchmark answers an isolated question without predicting a CLI win.
Re-verify daily, weekly, monthly, session, and blocks JSON after touching aggregation order, and record in the commit message any hotspot that was measured and deliberately left alone.

Node Paths

apps/ccusage/src/cli.js resolves and spawns the platform binary, so the JavaScript side is a startup-latency question rather than a throughput one — a profile of it covers launcher startup, not the work the binary does:

LOG_LEVEL=0 node --cpu-prof --cpu-prof-dir /tmp/ccusage-profiles apps/ccusage/src/cli.js daily --offline --json

Nothing else here runs on node. The tools under nix/tools/ are built with bunCli/bunNodeModules and run under Bun; scripts in apps/ccusage/scripts/ carry nix shell shebangs that pick nushell, babashka, or bun. Time those scripts directly and profile with their own runtime's tooling rather than NODE_OPTIONS.

Point --cpu-prof-dir outside the worktree — nothing here ignores a profiles/ directory.

Frequently asked questions

Profile