Is it possible you're going through a different proxy in headless vs. non-headless mode?

I had used the default Chromium configuration

But，`--proxy-bypass-list=*` really solved my problem。Reference from https://github.com/Codeception/CodeceptJS/issues/561

**macOS:** 10.13.4
**Node:** 8.10.0

I am also seeing a horrendous amount of time added to my requests when running `headless: true`.
Here is a simple code example;
```
(async () => {
  const browser = await puppeteer.launch({ headless: true });
  const promises = [];
  console.time('Timer');
  for (let i = 0; i < 10; i++) {
    promises.push(renderPage(browser));
  }
  await Promise.all(promises);
  console.timeEnd('Timer');
})();

const renderPage = async (browser: puppeteer.Browser) => {
  const page = await browser.newPage();
  await page.setViewport({ width: 1920, height: 1080 });
  await page.setContent('<h1>Some really simple HTML</h1>');
  const screenshot = await page.screenshot({ fullPage: true }); // Sets buffer but isn't used in this example.
  await page.close();
};
```

Running the above code with `headless: true` results in `7747.209ms`
Running the above code with `headless: false` results in `4775.771ms`

This is a HUGE difference in performance. Obviously I am working with more complex HTML than a simple <h1> tag and the disparity between the two modes is far greater.

@Reporter: From comment#3 i.e., "`--proxy-bypass-list=*` really solved my problem", we understood that the issue is no longer seen, Could you please let us know if we can close this issue.

Thanks!

As there isn't any Feedback from reporter since long time, closing this issue and marking it as Won't Fix.

@Reporter: Requesting you to file/raise a new issue if this issue is observed on the latest chrome versions.

Thanks!