For example, if a web page has three ad slots, will there be a big speed difference between the two methods?

Method 1：

Import adsbygoogle.js only once in the tag:

<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-xxxxxxxxxxx" crossorigin="anonymous"></script> 

After that, each ad unit in the page will no longer import the adsbygoogle.js file,only introduce:

<ins class="adsbygoogle" style="display:block" data-ad-client="ca-pub-xxxxxxxxxxx" data-ad-slot="xxxxxxxxxx" data-ad-format="auto" data-full-width-responsive="true"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> 

Method 2：

Each ad unit introduces the adsbygoogle.js file:

<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-xxxxxxxxxxx" crossorigin="anonymous"></script> 

<ins class="adsbygoogle"  style="display:block"  data-ad-client="ca-pub-xxxxxxxxxxx"  data-ad-slot="xxxxxxxxxx"  data-ad-format="auto"  data-full-width-responsive=" true"></ins> <script>  (adsbygoogle = window.adsbygoogle || []).push({});  </script> 

I used PageSpeed ​​Insights to analyze the performance of both, and it seems that there is not much difference。

You are welcome to suggest ways to test the performance of the two methods.