WP Super Cache won't speed up my site no matter what? What to do?

I just deleted the plugin WP super cache after spending hours watching “how to” videos of settings, changing settings etc. Tried PHP caching and Mod Rewrite. Neither made any diff. I’ve read all the forum posts about it. I verified that Super Cache was working. However it had no effect on the speed of my site. In fact it seemed that it was actually making the site slower. Can someone take a look through my site and maybe tell me if there’s something on it that would make it so slow. With or without super cache it was taking over 10 seconds to load. The only thing I can think of is that maybe because I have WP installed in a sub folder called “blog,” Super Cache doesn’t play well with it.

Here’s the URL: https://www.artsgraphics.com/blog/