optimization

A guide for making software faster, lighter, or more efficient. It starts by defining measurable targets and finding the parts of the system that use the most time or resources.

In plain words
What is it for?
Use it to investigate latency, throughput, memory, CPU use, startup time, build time, database queries, token use, or cost, then prioritize and verify improvements.
Why use it?
It prevents developers from changing code without evidence about the real bottleneck. Measurements and repeatable tests make it possible to check whether an improvement actually helped.

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/1jehuang/jcode/optimization
Any agent
npx skills add 1jehuang/jcode --skill optimization
Clone the repo
git clone --depth 1 https://github.com/1jehuang/jcode

Made for: Claude Code, Codex.

Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 692 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 $0.00052 $0.00692
Opus 5 $0.00026 $0.00346
Sonnet 5 $0.00010 $0.00138
Haiku 4.5 $0.00005 $0.00069

Measured yesterday against content hash fe0427bb421c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

optimization 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 yesterday.

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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

.jcode/skills/optimization/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Optimization

Use this skill when the task is about making a system faster, lighter, more scalable, or otherwise more efficient.

Core principle

To optimize properly, you must know:

  1. What metrics you are chasing
  2. What your real bottlenecks are

Do not optimize blindly.

1. Define the target metrics first

Before changing code, make sure you have the right measurements.

  • Identify the exact metrics that matter: latency, throughput, memory, CPU, startup time, compile time, query count, token usage, cost, etc.
  • Measure comprehensively, not just a convenient subset.
  • Make sure the metrics are accurate and representative of the real workload.
  • Prefer measurements that are fast to run so you can iterate quickly.
  • If possible, create repeatable benchmarks or scripts so improvements are verifiable.

2. Get full bottleneck attribution

You should have strong attribution for what each part of the system is doing.

  • Instrument the system so you can see where time and resources are going.
  • Prefer both:
    • Ad hoc inspection for quick debugging
    • Logged measurements for later analysis and comparison
  • Attribute work across the full path, not just the obviously slow component.
  • Make sure the data is detailed enough to explain where the cost comes from.

If you can analyze runs after the fact with logs or traces, that is often much more powerful than relying only on live inspection.

3. Use static analysis too

Not every optimization problem needs runtime profiling first. Often, code inspection reveals the issue.

Check for:

  • Wrong asymptotic complexity
  • The wrong algorithm or data structure
  • Unnecessary repeated work
  • Work happening in the wrong layer
  • Inefficient architecture or control flow
  • Directionally incorrect approaches

Make sure your asymptotics are right and the overall algorithm makes sense before tuning small details.

4. Macro-optimize before micro-optimizing

Prioritize the largest wins first.

  • Remove whole classes of work before making existing work slightly cheaper.
  • Fix architecture, batching, caching, query patterns, algorithm choice, parallelism, and data movement before focusing on tiny low-level tweaks.
  • If you are very far from the expected metrics, spend more time on macro-optimization.

Read the full file on GitHub · 85 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. yesterday First seen · 85 lines · 52 tokens per session scan A fe0427bb421c

Subscribe to this mod's changes

optimization is a skill published in the GitHub repository 1jehuang/jcode (18,821 stars, last pushed 2d ago), licensed MIT. It adds 52 tokens to every session and 692 once invoked, about $0.0003 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.