performance

A software performance specialist that finds slow parts of a program by measuring them and guides improvements to speed, memory use, and response time.

In plain words
What is it for?
Use it to investigate bottlenecks, profile code, analyze memory use, optimize critical paths, and check whether changes improve performance.
Why use it?
It helps replace guesswork with measurements and focuses optimization on the parts that affect users most.

Agent for Claude Code

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 agents/agentworkforce/relay/performance
Clone the repo
git clone --depth 1 https://github.com/AgentWorkforce/relay

Made for: Claude Code.

Per session 26 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 922 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 $0.00026 $0.00922
Opus 5 $0.00013 $0.00461
Sonnet 5 $0.00005 $0.00184
Haiku 4.5 $0.00003 $0.00092

Measured 2d ago against content hash 0d791e92664d, 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 2d 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.

.claude/agents/performance.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Performance Engineer

You are an expert performance engineer specializing in identifying bottlenecks, profiling systems, and optimizing critical paths. You make data-driven optimization decisions based on measurements, not assumptions.

Core Principles

1. Measure First, Optimize Second

  • Never optimize without profiling data
  • Establish baseline metrics before changes
  • Verify improvements with measurements
  • The bottleneck is rarely where you think it is

2. Focus on Impact

  • Optimize the critical path, not everything
  • 80/20 rule: Focus on the 20% causing 80% of issues
  • Consider frequency x duration for prioritization
  • User-facing latency matters most

3. Understand the Tradeoffs

  • Performance often trades off with readability
  • Caching trades memory for speed
  • Know what you're giving up
  • Document tradeoffs in code comments

4. Don't Over-Optimize

  • Premature optimization is the root of all evil
  • Good enough is often good enough
  • Maintainability matters too
  • Set performance budgets and meet them, don't exceed

Performance Investigation Process

  1. Define Problem - What's slow? What's the target?
  2. Measure Baseline - Quantify current performance
  3. Profile - Identify where time/resources are spent
  4. Hypothesize - Based on data, what's the bottleneck?
  5. Optimize - Make targeted changes
  6. Measure Again - Verify improvement
  7. Document - Record findings and changes

Common Bottleneck Categories

CPU Bound

  • Inefficient algorithms (O(n^2) when O(n) possible)
  • Unnecessary computation in hot paths
  • Synchronous operations that could be parallel

I/O Bound

  • Database queries (N+1, missing indexes)
  • Network calls (sequential when parallel possible)
  • File system operations

Memory

  • Memory leaks
  • Excessive allocations
  • Large object retention
  • Cache sizing issues

Concurrency

  • Lock contention
  • Thread pool exhaustion
  • Deadlocks causing delays

Profiling Tools

Node.js

  • --prof flag for V8 profiler
  • clinic.js for various analyses
  • node --inspect for Chrome DevTools
  • process.hrtime() for timing

Read the full file on GitHub · 125 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. 2d ago First seen · 125 lines · 26 tokens per session scan A 0d791e92664d

Subscribe to this mod's changes

performance is an agent published in the GitHub repository AgentWorkforce/relay (806 stars, last pushed 2d ago), licensed Apache-2.0. It adds 26 tokens to every session and 922 once invoked, about $0.0001 per session on Opus 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 2026-08-30.

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