Thank you again for your comments
I've used WebPagetest before many times in addition to some others. The output of it isn't as clear as to what steps can be made to improve issues like on gtmetrix or YSlow. Nevertheless, the main issues are pretty clear to me concerning vB - loading static content better.
It's interesting you say that the JS files are actually loading in parallel, which is something I thought was a big problem for vB. I also have a handful of other JS code/files related to Tapatalk and Mathjax. In terms of just moving all JS, CSS and images to a CDN without any further tweaking - how much of an improvement do you think this could make? I really wish we had some "before and after" data to look at.
Trying to make real changes to my site that result in better speeds is something that has been like a theoretical marathon of reading about different strategies but not knowing how to do them. I would like to try to implement something at last, but need guidance where to start.