能否在Chrome DevTools设置自定义CPU节流？含Lighthouse参数验证咨询

Great question! Let's break down your concerns one by one:

1. Does Chrome 63's DevTools Performance panel support custom CPU throttling (like 20x)? #

Out of the box, Chrome 63's Performance panel only offers the three preset options: No throttling, 4x slowdown, and 6x slowdown. There's no native UI to input a custom multiplier like 20x directly in the panel.

2. Can custom throttling be achieved via chrome.exe launch flags or Node.js libraries? #

Chrome.exe launch flags #

Unfortunately, there's no direct launch flag in Chrome 63 to set a custom CPU throttling multiplier. Flags like --force-low-power-mode or --disable-highres-timers affect performance in general but don't let you specify an exact 20x slowdown.

Node.js libraries (e.g., Puppeteer) #

Yes, you can use Puppeteer (a Node.js library that controls Chrome via the DevTools Protocol) to set any custom CPU throttling rate. Note that you'll need a Puppeteer version compatible with Chrome 63 (likely Puppeteer v1.x, since newer versions require newer Chrome builds).

Here's a quick example:

const puppeteer = require('puppeteer');

(async () => {
  // Launch Chrome 63 (specify executable path if needed)
  const browser = await puppeteer.launch({
    executablePath: 'C:/Program Files (x86)/Google/Chrome/Application/chrome.exe',
    headless: false, // Open visible browser to verify
    defaultViewport: null
  });

  const page = await browser.newPage();
  // Set 20x CPU throttling
  await page.emulateCPUThrottling(20);

  // Navigate to your test page
  await page.goto('https://example.com');

  // Run your tests or record performance profiles here
  // ...

  await browser.close();
})();

3. How to verify if Lighthouse's modified CPU_THROTTLE_METRICS (set to 20) is working? #

If you've modified Lighthouse's default CPU_THROTTLE_METRICS from 4 to 20, here are three reliable ways to confirm it's active:

• Check verbose logs: Run Lighthouse with the --verbose flag. Look for a log line like CPU throttling rate: 20—this confirms the multiplier was applied.
• Inspect the Lighthouse report JSON: Export the report as JSON (using --output json flag) and look for the configSettings.cpuThrottlingMultiplier field. It should show 20.
• Manual performance validation: Record a Performance profile while Lighthouse runs. Compare the execution time of key tasks (e.g., script evaluation, layout) against a non-throttled run. A task that takes 100ms normally should take ~2000ms with 20x throttling, which confirms the setting is working.

内容的提问来源于stack exchange，提问作者ScriptyChris