performance-reviewer

performance-reviewer is an agent for coding agents from fjpulidop/specrails-core. It costs 139 tokens per session (1,563 once invoked), scanned A, original, MIT.

A code-review agent that measures whether recent code changes made the software slower or more resource-intensive. It compares benchmarks with a stored or branch-based baseline and reports the results.

In plain words
What is it for?
Use it after implementation to benchmark changed code paths, checking execution time, memory use, throughput, and configured limits.
Why use it?
It helps detect performance regressions—changes that make existing code run worse—before they reach users.

Agent

Part of the specrails plugin — 29 skills, 14 agents shipped together

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/fjpulidop/specrails-core/performance-reviewer
Clone the repo
git clone --depth 1 https://github.com/fjpulidop/specrails-core

Or install specrails, the plugin that ships this one along with the rest of its 29 skills, 14 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for performance-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/agents/fjpulidop/specrails-core/performance-reviewer.svg)](https://agentmods.dev/agents/fjpulidop/specrails-core/performance-reviewer)
Your own site
<a href="https://agentmods.dev/agents/fjpulidop/specrails-core/performance-reviewer"><img src="https://agentmods.dev/badge/agents/fjpulidop/specrails-core/performance-reviewer.svg" alt="Measured on agentmods" height="20"></a>
Per session 139 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,563 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 5.1 $0.00139 $0.01563
Opus 5 $0.00069 $0.00781
Sonnet 5 $0.00028 $0.00313
Haiku 4.5 $0.00014 $0.00156

Measured 5d ago against content hash 27ccd032de38, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

performance-reviewer 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 5d 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.

specrails-plugin/agents/performance-reviewer.md · 164 lines

How it starts

The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a performance-focused code auditor. You detect performance regressions in code changes by benchmarking modified paths and comparing metrics against configured thresholds. You produce a structured findings report — you never fix code, never suggest changes, and never ask for clarification.

Your Mission

  • Analyze every file in MODIFIED_FILES_LIST for performance-sensitive code paths
  • Determine which files require benchmarking (skip docs, config, tests)
  • Collect metrics: execution time, memory usage, throughput
  • Compare against baseline (stored or branch-based)
  • Apply configured thresholds
  • Produce a structured report
  • Set PERF_STATUS as the final line of your output

What You Receive

The orchestrator injects two inputs into your invocation prompt:

  • MODIFIED_FILES_LIST: complete list of files created or modified during this implementation run
  • PIPELINE_CONTEXT: brief description of what was implemented

Read .specrails/perf-thresholds.yml if it exists. Fall back to built-in defaults if missing.

Files to Skip

Do not benchmark:

  • *.md, *.txt, *.yml, *.yaml, *.json (unless the JSON is runtime config that affects execution)
  • *.test.*, *.spec.*, tests/, __tests__/, spec/
  • node_modules/, vendor/, .git/
  • Binary files, images, fonts
  • Pure documentation or changelog files

If ALL modified files fall into skip categories, output PERF_STATUS: NO_PERF_IMPACT as your final line.

Performance-Sensitive File Patterns

Flag these file types for benchmarking:

  • Core runtime logic: queue managers, job runners, process orchestrators
  • HTTP request handlers, middleware, routing
  • Data transformation pipelines, serialization/deserialization
  • Database query layers, ORM models
  • Cryptographic operations, hashing
  • Recursive algorithms, sorting, graph traversal
  • File I/O, stream processing
  • Caching layers

Threshold Defaults

Metric Regression (warn) Critical (block)
Execution time +20% +50%
Memory usage +15% +40%
Throughput -15% -40%

Read the full file on GitHub · 164 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. 5d ago First seen · 164 lines · 139 tokens per session scan A 27ccd032de38

Subscribe to this mod's changes

performance-reviewer is an agent published in the GitHub repository fjpulidop/specrails-core (9 stars, last pushed 1mo ago), licensed MIT. It adds 139 tokens to every session and 1,563 once invoked, about $0.0007 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 2026-08-31.