Yes I visited the website that’s why I made the last paragraph ??
Unfortunately, there’s not much that can be done because when MAB (or any other display plugin) is used as a widget, stylesheets are loaded down at the bottom of the page instead of at the top where styles are usually loaded. This is because a page won’t know there’s a widget until it is rendered on the page and the accompanying stylesheet is added by then (and not before).
I did notice that the images on the website loaded a bit more slowly than what I’d expect. Checking out the images, they were pretty big by web standards. two of the banner images alone took up almost 2mb.
I ran a quick page load test on your home page. Here are the results: https://imgur.com/FPR5kVo 15 seconds to complete. That’s quite long.
You might be wondering what this has to do with MAB. Remember what I said about the form is up top and the stylesheet is down at the end? Well, between the two is the rest of the page, notably the images. The faster you can render the rest of the page, the faster the stylesheet down at the end can load.