I didn't mention much in the thread because I was otherwise distracted, but I have to say that your site speed has improved tremendously. After my own headaches with disk crashes and a failing SSD that had to be replaced, I didn't care that the old s/w was slow to load. The fact that it loaded at all was good. But now that my PC has settled down and stabilized, my extra memory and the SSD have combined to make things much faster. Add to that the idea that you have been tweaking with caches and finding a good distribution for DNS sits and I have to say that at times this site will load in less than a second. Page switches within the site are nearly instantaneous.
Jon, based on some of the comments I caught up on, you should feel free to ask me questions if you run across networking or security terms you don't understand. I can't claim to be a UNIX sys engineer but I do know two other O/S internals to different degrees and can discuss at least some concepts if you have a problem. No guarantees because different implementations of TCP/IP stacks and UNIX O/S exist and each one has its quirks, but I don't mind helping you. And if I can't help directly, I might still be able to come up with a web link or two.