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.
npx agentmods add skills/areu01or00/perf-hints/performance-hintsnpx skills add areu01or00/perf-hints --skill performance-hintsgit clone --depth 1 https://github.com/areu01or00/perf-hintsWrote 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.
[](https://agentmods.dev/skills/areu01or00/perf-hints/performance-hints)<a href="https://agentmods.dev/skills/areu01or00/perf-hints/performance-hints"><img src="https://agentmods.dev/badge/skills/areu01or00/perf-hints/performance-hints.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00089 | $0.00703 |
| Opus 5 | $0.00044 | $0.00351 |
| Sonnet 5 | $0.00018 | $0.00141 |
| Haiku 4.5 | $0.00009 | $0.00070 |
Grade A, and why
performance-hints 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Perf-Hints
Language-agnostic engineering wisdom from Google's Abseil - performance optimization, code review, testing, and software engineering practices.
Philosophy
"In established engineering disciplines a 12% improvement, easily obtained, is never considered marginal." — Donald Knuth
Don't dismiss small improvements. Twenty 1% improvements compound significantly.
Why "Optimize Later" Fails
- Flat profile problem - Performance lost everywhere, no obvious hotspot
- Library users suffer - They can't easily fix your slow code
- Heavy use constrains changes - Harder to change systems in production
- Expensive workarounds - Teams overprovision instead of fixing
Reference Routing
Consult the appropriate reference file based on the task:
| User asks about | Reference file |
|---|---|
| Back-of-envelope, estimation, costs | references/when-estimating.md |
| Profiling, benchmarking, measurement | references/when-measuring-performance.md |
| Memory, allocations, cache, GC | references/when-optimizing-memory.md |
| "Why is this slow?", debugging perf | references/when-debugging-perf.md |
| Code review, PR review | references/when-reviewing-code.md |
| Testing, unit tests, mocking | references/when-writing-tests.md |
| API design, interfaces, libraries | references/when-designing-apis.md |
| Scaling, migrations, deprecation | references/when-scaling.md |
| Finding a specific article | references/index.md |
Quick Reference
Latency Numbers
L1 cache 0.5 ns
Main memory 50 ns
Datacenter round trip 50 μs
Read 1MB memory 64 μs
Read 1MB SSD 1 ms
Disk seek 5 ms
Common Bottlenecks
| Issue | Pattern | Fix |
|---|---|---|
| Sequential I/O | for + await |
Parallelize |
| Client per request | async with Client() |
Share client |
| N+1 queries | Loop of DB calls | Batch query |
| Hot loop allocations | Object in loop | Pre-allocate |
What ships with it
9 files 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.
- references/index.md 5.4 KB
- references/when-debugging-perf.md 1.1 KB
- references/when-designing-apis.md 1.3 KB
- references/when-estimating.md 766 B
- references/when-measuring-performance.md 1.2 KB
- references/when-optimizing-memory.md 969 B
- references/when-reviewing-code.md 1.2 KB
- references/when-scaling.md 1.1 KB
- references/when-writing-tests.md 876 B
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.
- 3d ago First seen · 70 lines · 89 tokens per session scan A 7dc7f60b81bc
performance-hints is a skill published in the GitHub repository areu01or00/perf-hints (4 stars, last pushed 8mo ago), licensed MIT. It adds 89 tokens to every session and 703 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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