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 skills add heyAyushh/stacc --skill performancegit clone --depth 1 https://github.com/heyAyushh/staccWrote 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/heyayushh/stacc/performance)<a href="https://agentmods.dev/skills/heyayushh/stacc/performance"><img src="https://agentmods.dev/badge/skills/heyayushh/stacc/performance/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/heyayushh/stacc/performance"><img src="https://agentmods.dev/badge/skills/heyayushh/stacc/performance.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00037 | $0.00715 |
| Opus 5 | $0.00018 | $0.00358 |
| Sonnet 5 | $0.00007 | $0.00143 |
| Haiku 4.5 | $0.00004 | $0.00072 |
Grade A, and why
rust-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 9d 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 — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Performance Optimization
Layer 2: Design Choices
Core Question
What's the bottleneck, and is optimization worth it?
Before optimizing:
- Have you measured? (Don't guess)
- What's the acceptable performance target?
- Will optimization add significant complexity?
Thinking Prompt
-
Have you measured?
- Profile first → flamegraph, perf
- Benchmark → criterion,
cargo bench - Identify actual hotspots
-
What's the priority?
- Algorithm (10x–1000x improvement)
- Data structure (2x–10x)
- Allocation reduction (2x–5x)
- Cache optimization (1.5x–3x)
-
What's the trade-off?
- Complexity vs speed
- Memory vs CPU
- Latency vs throughput
Optimization Priority
1. Algorithm choice (10x - 1000x)
2. Data structure (2x - 10x)
3. Allocation reduction (2x - 5x)
4. Cache optimization (1.5x - 3x)
5. SIMD/Parallelism (2x - 8x)
Common Techniques
| Technique | When | How |
|---|---|---|
| Pre-allocation | Known size | Vec::with_capacity(n) |
| Avoid cloning | Hot paths | Use references or Cow<T> |
| Batch operations | Many small ops | Collect then process |
| SmallVec | Usually small | smallvec::SmallVec<[T; N]> |
| Inline buffers | Fixed-size data | Arrays over Vec |
Tooling
| Tool | Purpose |
|---|---|
cargo bench |
Micro-benchmarks |
criterion |
Statistical benchmarks |
perf / flamegraph |
CPU profiling |
heaptrack |
Allocation tracking |
valgrind / cachegrind |
Cache analysis |
Common Mistakes
| Mistake | Why Wrong | Better |
|---|---|---|
| Optimize without profiling | Wrong target | Profile first |
| Benchmark in debug mode | Meaningless results | Always --release |
Use LinkedList |
Cache unfriendly | Vec or VecDeque |
Hidden .clone() in loop |
Unnecessary allocs | Use references |
| Premature optimization | Wasted effort | Make it correct first |
Anti-Patterns
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.
- 9d ago First seen · 105 lines · 37 tokens per session scan A 1af1843dba19
rust-performance is a skill published in the GitHub repository heyAyushh/stacc (3 stars, last pushed 2mo ago), licensed MIT. It adds 37 tokens to every session and 715 once invoked, about $0.0002 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 2026-09-03.
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