Translation Comparison - optimizing-code

When optimizing, you improve performance without changing behavior. Always measure before and after.

进行优化时，你需要在不改变行为的前提下提升性能。优化前后务必进行测量。

Golden Rules

黄金法则

Measure First: Never optimize without a benchmark
Profile Before Guessing: Find the actual bottleneck
Optimize the Right Thing: Focus on the critical path
Measure After: Verify the optimization worked

先测量（Measure First）：绝不进行无Benchmark的优化
先Profiling再猜测（Profile Before Guessing）：找到真正的性能瓶颈
优化正确的部分（Optimize the Right Thing）：聚焦关键路径
后测量（Measure After）：验证优化是否有效

Workflows

工作流程

Benchmark: Establish baseline performance metrics
Profile: Identify the actual bottleneck
Hypothesize: What optimization will help?
Implement: Make the change
Measure: Verify improvement
Document: Record the optimization and results

Benchmark：建立基准性能指标
Profiling：识别真正的性能瓶颈
提出假设：哪种优化方法会有效？
实施：进行修改
测量：验证优化效果
文档记录：记录优化内容和结果

Common Optimizations

常见优化手段

Algorithm Complexity

算法复杂度

Replace O(n²) with O(n log n) or O(n)
Use appropriate data structures (Set for lookups, Map for key-value)

用O(n log n)或O(n)复杂度的算法替代O(n²)
使用合适的数据结构（Set用于查找，Map用于键值对存储）

typescript

// Memoization
const cache = new Map<string, Result>();

function expensiveCalculation(input: string): Result {
  if (cache.has(input)) {
    return cache.get(input)!;
  }
  const result = /* expensive work */;
  cache.set(input, result);
  return result;
}

typescript

// Memoization
const cache = new Map<string, Result>();

function expensiveCalculation(input: string): Result {
  if (cache.has(input)) {
    return cache.get(input)!;
  }
  const result = /* expensive work */;
  cache.set(input, result);
  return result;
}

Database Queries

数据库查询

Add indexes for frequently queried columns
Avoid N+1 queries (use eager loading)
Use pagination for large result sets

为频繁查询的字段添加索引
避免N+1查询（使用预加载）
对大型结果集使用分页

Avoid creating unnecessary objects in loops
Use streaming for large files
Release references when done

避免在循环中创建不必要的对象
对大文件使用流处理
不再使用时释放引用

Profiling Tools

Profiling工具

bash

undefined

bash

undefined

node --prof app.js node --prof-process isolate-*.log

python -m cProfile -s cumtime script.py

go test -bench=. -cpuprofile=cpu.prof go tool pprof cpu.prof

undefined

go test -bench=. -cpuprofile=cpu.prof go tool pprof cpu.prof

undefined

Anti-Patterns to Avoid

需避免的反模式

Premature optimization (no benchmark)
Micro-optimizations (negligible impact)
Optimizing cold paths
Sacrificing readability for minor gains

过早优化（无Benchmark）
微优化（影响可忽略）
优化冷路径
为微小收益牺牲可读性

optimizing-code

Original

Translation

Optimizing Code

代码优化

The Optimization Hat

优化准则