Is there any external javascript file that takes too long to respond before timing out?

Not sure if this is the right place to ask this question, so please guide if we have any other communities for this.

We had an issue earlier when one of our external script, pingdom didn't load because of some networking glitch at their end. During this time, the browser waited for response from the request and timed out after 2 mins.

For this entire duration, the website was loading which increased our average page load time.

We made a fix to prevent the site from waiting for the response in case if this happens again and now we want to test this but not sure where I can find a external script that takes too long to respond or if we can make one.