Summary - Performance

Combine perf_hooks, memoryUsage and profiling to write a benchmark tool.

Summary - Performance

In this group you learned performance tools: time measurement with perf_hooks, memory monitoring with process.memoryUsage(), CPU profiling with inspector. Event loop latency is an early warning for bottlenecks.

The optimization order: measure, find the bottleneck, remove it, measure again. Move CPU work to a worker thread, make I/O asynchronous, cache repeated calculations. Avoid premature optimization; always rely on data.

Performance checklist

Performance checklist: (1) Event loop latency should be under 10 ms. (2) heapUsed should grow steadily, without leaks. (3) CPU profiles should show the bottleneck function. (4) Response times should be consistent.

In production, APM tools (New Relic, Datadog) collect these metrics automatically. Adding your own measurements is a good habit; but use existing tools first.

Exercise Check if now is a function

Import performance from perf_hooks. Log typeof performance.now === "function".

Show example solution

const { performance } = require("perf_hooks");
console.log(typeof performance.now === "function");

Test yourself

What is the first step before optimization?
- Kodu yeniden yazmak
- Measuring (profiling)
- Installing a new module
- Switching servers
Show answer

Measuring (profiling) — Measure first, then improve.
Match each piece to its role

perf_hooks

Measures time
process.memoryUsage()

Gives memory
inspector

CPU profile
event loop latency

Measures delay

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