better-performance

A method for improving software speed and resource use by measuring how it runs. It covers costs such as response time, memory, CPU use, database queries, network calls, and downloaded bundle size.

In plain words
What is it for?
Use it to investigate slow requests, high CPU or memory use, repeated queries or network calls, large bundles, blocking input/output, and resource growth. It can guide work from profilers, benchmarks, traces, production metrics, query plans, or bundle reports.
Why use it?
It prevents guesswork by requiring evidence of a real performance problem before changing code. This keeps optimisation focused on a measured workload or a clearly established scaling issue.

Skill for Claude CodeCodex

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 skills/nicolasyusim/better-codebase/better-performance
Any agent
npx skills add NicolasYusim/better-codebase --skill better-performance
Clone the repo
git clone --depth 1 https://github.com/NicolasYusim/better-codebase

Made for: Claude Code, Codex.

Per session 79 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,210 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 $0.00079 $0.01210
Opus 5 $0.00039 $0.00605
Sonnet 5 $0.00016 $0.00242
Haiku 4.5 $0.00008 $0.00121

Measured 2d ago against content hash 719f5ab8f848, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

better-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.

skills/better-performance/SKILL.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Improve performance only where evidence points

Optimize against an explicit workload, constraint, or established complexity problem. Protect correctness and clarity while reducing a measured cost.

Own proven performance problems

Own latency, throughput, CPU, memory, allocation, I/O, query, network, serialization, bundle, and scaling findings supported by measurement or a clearly established complexity issue.

Do not own general code cleanliness, dependency freshness, or architectural preference. Route those root causes to their owning skills and mention performance only as a secondary effect when it is not measured.

Evidence gate

Accept a performance finding only with at least one:

  • profiler, trace, query plan, bundle report, or production metric tied to the scope;
  • reproducible benchmark using a representative workload;
  • observed call or query count that establishes repeated work;
  • demonstrated resource growth or leak;
  • a complexity argument with realistic unbounded or sufficiently large input;
  • a documented latency, memory, throughput, or size budget that the current result exceeds.

Source-code suspicion without one of these becomes a measurement candidate, not a finding.

Review workflow

1. Define the performance contract

Identify the workload, input size, concurrency, environment, warm or cold state, cache state, percentile or aggregate, and required budget. State what users or systems experience when the budget is missed.

If no contract exists, define a measurement question instead of inventing a target.

2. Establish the baseline

Use existing benchmarks, observability, profilers, database tooling, browser tooling, or package analyzers where available. Keep measurement safe and proportionate.

Record:

  • exact command or interaction;
  • environment and representative fixture;
  • repetitions, warmup, and variance when meaningful;
  • baseline time, memory, count, throughput, or size;
  • important exclusions and noise sources.

Read the full file on GitHub · 139 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 139 lines · 79 tokens per session scan A 719f5ab8f848

Subscribe to this mod's changes

better-performance is a skill published in the GitHub repository NicolasYusim/better-codebase (1 stars, last pushed 23d ago), licensed MIT. It adds 79 tokens to every session and 1,210 once invoked, about $0.0004 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.

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