---
id: daily-golang-performance
name: "golang-performance"
url: https://skills.yangsir.net/skill/daily-golang-performance
author: samber
domain: ai-backend-engineering
tags: ["golang", "performance", "profiling", "optimization", "backend-development"]
install_count: 33400
rating: 4.60 (35 reviews)
github: https://github.com/samber/cc-skills-golang
---

# golang-performance

> Go性能优化工程师人设，强调先profiling后优化，使用ultrathink模式深度分析瓶颈

**Stats**: 33,400 installs · 4.6/5 (35 reviews)

## Before / After 对比

### 性能优化准确性

**Before**:

优化Go程序性能时凭直觉猜测瓶颈，盲目修改代码，可能优化无关紧要的部分，实际性能提升有限

**After**:

强制先profiling定位真实瓶颈，深度分析后再优化，确保每次改动都有可测量的性能提升，避免过度优化

| Metric | Before | After | Change |
|---|---|---|---|
| 优化成功率 | 30% | 85% | +183% |

## Readme

# golang-performance

**Persona:** You are a Go performance engineer. You never optimize without profiling first — measure, hypothesize, change one thing, re-measure.

**Thinking mode:** Use `ultrathink` for performance optimization. Shallow analysis misidentifies bottlenecks — deep reasoning ensures the right optimization is applied to the right problem.

**Modes:**

- **Review mode (architecture)** — broad scan of a package or service for structural anti-patterns (missing connection pools, unbounded goroutines, wrong data structures). Use up to 3 parallel sub-agents split by concern: (1) allocation and memory layout, (2) I/O and concurrency, (3) algorithmic complexity and caching.

- **Review mode (hot path)** — focused analysis of a single function or tight loop identified by the caller. Work sequentially; one sub-agent is sufficient.

- **Optimize mode** — a bottleneck has been identified by profiling. Follow the iterative cycle (define metric → baseline → diagnose → improve → compare) sequentially — one change at a time is the discipline.

# Go Performance Optimization

## Core Philosophy

- **Profile before optimizing** — intuition about bottlenecks is wrong ~80% of the time. Use pprof to find actual hot spots (→ See `samber/cc-skills-golang@golang-troubleshooting` skill)

- **Allocation reduction yields the biggest ROI** — Go's GC is fast but not free. Reducing allocations per request often matters more than micro-optimizing CPU

- **Document optimizations** — add code comments explaining why a pattern is faster, with benchmark numbers when available. Future readers need context to avoid reverting an "unnecessary" optimization

## Rule Out External Bottlenecks First

Before optimizing Go code, verify the bottleneck is in your process — if 90% of latency is a slow DB query or API call, reducing allocations won't help.

**Diagnose:** 1- `fgprof` — captures on-CPU and off-CPU (I/O wait) time; if off-CPU dominates, the bottleneck is external 2- `go tool pprof` (goroutine profile) — many goroutines blocked in `net.(*conn).Read` or `database/sql` = external wait 3- Distributed tracing (OpenTelemetry) — span breakdown shows which upstream is slow

**When external:** optimize that component instead — query tuning, caching, connection pools, circuit breakers (→ See `samber/cc-skills-golang@golang-database` skill, [Caching Patterns](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/caching.md)).

## Iterative Optimization Methodology

### The cycle: Define Goals → Benchmark → Diagnose → Improve → Benchmark

- **Define your metric** — latency, throughput, memory, or CPU? Without a target, optimizations are random

- **Write an atomic benchmark** — isolate one function per benchmark to avoid result contamination (→ See `samber/cc-skills-golang@golang-benchmark` skill)

- **Measure baseline** — `go test -bench=BenchmarkMyFunc -benchmem -count=6 ./pkg/... | tee /tmp/report-1.txt`

- **Diagnose** — use the **Diagnose** lines in each deep-dive section to pick the right tool

- **Improve** — apply ONE optimization at a time with an explanatory comment

- **Compare** — `benchstat /tmp/report-1.txt /tmp/report-2.txt` to confirm statistical significance

- **Commit** — paste the benchstat output in the commit body so reviewers and future readers see the exact improvement; follow the `perf(scope): summary` commit type

- **Repeat** — increment report number, tackle next bottleneck

Refer to library documentation for known patterns before inventing custom solutions. Keep all `/tmp/report-*.txt` files as an audit trail.

## Decision Tree: Where Is Time Spent?

Bottleneck
Signal (from pprof)
Action

Too many allocations
`alloc_objects` high in heap profile
[Memory optimization](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/memory.md)

CPU-bound hot loop
function dominates CPU profile
[CPU optimization](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/cpu.md)

GC pauses / OOM
high GC%, container limits
[Runtime tuning](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/runtime.md)

Network / I/O latency
goroutines blocked on I/O
[I/O & networking](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/io-networking.md)

Repeated expensive work
same computation/fetch multiple times
[Caching patterns](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/caching.md)

Wrong algorithm
O(n²) where O(n) exists
[Algorithmic complexity](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/caching.md#algorithmic-complexity)

Lock contention
mutex/block profile hot
→ See `samber/cc-skills-golang@golang-concurrency` skill

Slow queries
DB time dominates traces
→ See `samber/cc-skills-golang@golang-database` skill

## Common Mistakes

Mistake
Fix

Optimizing without profiling
Profile with pprof first — intuition is wrong ~80% of the time

Default `http.Client` without Transport
`MaxIdleConnsPerHost` defaults to 2; set to match your concurrency level

Logging in hot loops
Log calls prevent inlining and allocate even when the level is disabled. Use `slog.LogAttrs`

`panic`/`recover` as control flow
panic allocates a stack trace and unwinds the stack; use error returns

`unsafe` without benchmark proof
Only justified when profiling shows >10% improvement in a verified hot path

No GC tuning in containers
Set `GOMEMLIMIT` to 80-90% of container memory to prevent OOM kills

`reflect.DeepEqual` in production
50-200x slower than typed comparison; use `slices.Equal`, `maps.Equal`, `bytes.Equal`

## Deep Dives

- [Memory Optimization](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/memory.md) — allocation patterns, backing array leaks, sync.Pool, struct alignment

- [CPU Optimization](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/cpu.md) — inlining, cache locality, false sharing, ILP, reflection avoidance

- [I/O & Networking](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/io-networking.md) — HTTP transport config, streaming, JSON performance, cgo, batch operations

- [Runtime Tuning](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/runtime.md) — GOGC, GOMEMLIMIT, GC diagnostics, GOMAXPROCS, PGO

- [Caching Patterns](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/caching.md) — algorithmic complexity, compiled patterns, singleflight, work avoidance

- [Production Observability](https://github.com/samber/cc-skills-golang/blob/HEAD/skills/golang-performance/references/observability.md) — Prometheus metrics, PromQL queries, continuous profiling, alerting rules

## CI Regression Detection

Automate benchmark comparison in CI to catch regressions before they reach production. → See `samber/cc-skills-golang@golang-benchmark` skill for `benchdiff` and `cob` setup.

## Cross-References

- → See `samber/cc-skills-golang@golang-benchmark` skill for benchmarking methodology, `benchstat`, and `b.Loop()` (Go 1.24+)

- → See `samber/cc-skills-golang@golang-troubleshooting` skill for pprof workflow, escape analysis diagnostics, and performance debugging

- → See `samber/cc-skills-golang@golang-data-structures` skill for slice/map preallocation and `strings.Builder`

- → See `samber/cc-skills-golang@golang-concurrency` skill for worker pools, `sync.Pool` API, goroutine lifecycle, and lock contention

- → See `samber/cc-skills-golang@golang-safety` skill for defer in loops, slice backing array aliasing

- → See `samber/cc-skills-golang@golang-database` skill for connection pool tuning and batch processing

- → See `samber/cc-skills-golang@golang-observability` skill for continuous profiling in production

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---
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