Website pages with jQuery won't load in Firefox but load in Chrome

I took over development for an old website recently and the page doesn’t load for me in Firefox but it does load in Chrome. In Firefox the pages load part way and then after a few minutes Firefox warns me “This page slowing down Firefox. To speed up your browser, stop this page.”

I can’t see an exact cause but pages load when I comment out the code that loads jQuery so I assume it’s related:

<script type="text/javascript" src="" />

I can’t see any errors in the dev tools console (at least that I am able to decipher) to help me with the issue.

There are no problems loading jQuery with these pages in Chrome/Chromium - everything works on the website as planned.

Why does this problem occur in Firefox and why does it not occur in Chrome?

Thanks for your help.

I used Firefox profiler (without really knowing what it does) while loading this page and upon capture the profiler helpfully highlighted part of a function in the file jquery.multiple-bgs.js. When I renamed the file the pages load correctly and jQuery appears to be functioning on the site in all the places that I am aware of that use it.

So I suppose the location of the problem is in that file, though I am only a little bit closer finding out the actual cause and why only Firefox has a problem with it and not Chrome.