One of 22 sites slow to respond

I run 22 WP sites and I have one site that is slow as slow can be on every computer I’ve tested it on. https://www.johnhoosehunting.com is the site. I’m being told by 1&1 my provider that it runs just fine on their systems. I’ve reset our AT&T router here and cleared caches and it still runs so slow sometimes it won’t even come up their response was:

“Regarding to your concern, we have checked your website and we found out that you are using a word press for it. Please be advised to check the content/script of your website. Please refer to word press forums about the causes for your website to upload slowly. However on other case on 1&1 servers, there is no problems with our server.”

What does uploading have to do with downloading the site for people to see? Are they just putting me off does anyone else have problems with the site loading properly?

Any feedback would be much appreciated.