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/muratmirgun/gophers/go-performancenpx skills add muratmirgun/gophers --skill go-performancegit clone --depth 1 https://github.com/muratmirgun/gophersWrote 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/muratmirgun/gophers/go-performance)<a href="https://agentmods.dev/skills/muratmirgun/gophers/go-performance"><img src="https://agentmods.dev/badge/skills/muratmirgun/gophers/go-performance.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 | $0.02041 |
| Opus 5 | $0.00044 | $0.01020 |
| Sonnet 5 | $0.00018 | $0.00408 |
| Haiku 4.5 | $0.00009 | $0.00204 |
Grade A, and why
go-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 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.
How it starts
The opening of the file, as written. The whole thing — 187 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Go Performance
Performance work in Go follows one rule: measure first. Intuition about bottlenecks is wrong roughly 80% of the time. Profile, hypothesise, change one thing, re-measure. The patterns in this skill apply only on hot paths — premature optimisation makes code worse without making it faster.
Core Rules
- Profile before optimising.
go test -bench,pprof,fgprof— never guess. - One change at a time. Multi-change "optimisation" passes are unreviewable.
- Compare with
benchstat. Single runs lie; you need ≥6 runs to see signal. - Allocation reduction usually beats CPU micro-optimisation — the GC is fast but not free.
- Rule out external bottlenecks first. If 90% of latency is the DB, faster Go code is irrelevant.
- Document optimisations in comments. Future readers will revert "ugly" code without context.
Iterative Methodology
The cycle is: define goal → write benchmark → measure baseline → diagnose → improve one thing → re-measure → commit with the diff.
# baseline
go test -bench=BenchmarkHotPath -benchmem -count=6 ./pkg/... | tee /tmp/report-1.txt
# (apply ONE change)
# compare
go test -bench=BenchmarkHotPath -benchmem -count=6 ./pkg/... | tee /tmp/report-2.txt
benchstat /tmp/report-1.txt /tmp/report-2.txt
If benchstat shows no statistically significant change, the optimisation didn't work — revert it. Keep the /tmp/report-*.txt files as an audit trail; paste the benchstat output in the commit body.
Read references/benchmarking-and-pprof.md for benchmark writing, pprof workflow, and
b.Loop()(Go 1.24+).
Rule Out External Bottlenecks First
Before optimising any Go code, check that the bottleneck is actually in your process:
fgprof— captures on-CPU and off-CPU (I/O wait) time. If off-CPU dominates, the issue is elsewhere.- Goroutine profile — many goroutines blocked in
net.(*conn).Readordatabase/sqlmeans external I/O is the limit. - Distributed tracing — span breakdown shows which upstream is slow.
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.
- 5d ago First seen · 187 lines · 89 tokens per session scan A e8dbde142911
go-performance is a skill published in the GitHub repository muratmirgun/gophers (8 stars, last pushed 24d ago), licensed MIT. It adds 89 tokens to every session and 2,041 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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