This is due to custom code snippets that you've added, including at least three versions of jQuery which shouldn't be there and could slow down your site unnecessarily.
I recommend you remove all the code (from Code Injection) and then test again. The problem should disappear. you can then carefully add code one section at a time until you identify which section is causing the problem. I do recommend being very cautious about installing code that you don't understand as it could affect your site's reliability and security.