Very Slow Page Loading after Initializing FF Portable v49

I created a new profile with a new name. I changed the old name of the "Data" directory to "Data_bak". I renamed the new profile to "Data". I made sure the target of this hard-link directory contained the new profile data. Everything worked fine. I then copied about 10 files from my backed up directory to the new directory to keep my settings. All works fine, but I'm still having the slowness (spinning) problem; not all the time but maybe 25% of the time. I use Symantec SEP-SBE Cloud. I understand it uses the Windows 10 firewall so I checked on the applications this firewall allows and noticed that Firefox (and portable) weren't included. So, I added the FirefoxPortable.exe as an authorized app and the Firefox.exe, within the portable directory, as an authorized app. This helps greatly, but I'm now having the problem maybe 15% of the time. When I have the problem, turning off the firewall works about 1 in 3 times. When I have the problem, if i copy the URL into Chrome (or IE) the page comes up immediately in one of these browsers and then, after a few seconds, comes up in Firefox. This happens about 1 in 3 times the problem occurs. For those time when the previous two steps don't work, if I wait 1-2 minutes the page will eventually come up in Firefox.

Whenever I open Firefox without add-ons I don't have this problem. I have removed all add-ons and there is still something causing problems even when I request all plugins to "Never Activate".

Is there any way I can isolate the problem while firefox is running or will I have to completely rebuild all my settings and configurations within a clean profile (or move to Chrome Portable)?

So, now my FF directory contains two data directories; Data_local and Data_symlink. The contents of the symlink directory have been copied into the local directory. The symlink is a true symlink to a network location (high-speed) and the local is in the firefox directory.

When I use the local directory Firefox is very speedy, whether I'm on the "wired" network or on the "wireless" network. When I'm using the symlink data directory on the "wired" network Firefox is slower but seems to, almost, learn and gets satisfactorily responsive after several minutes navigating. However, on the "wireless" network Firefox becomes unusable, although the initial load of Firefox, with all the bookmarks, etc, accessing the single home page works as quickly as one would expect. It's just when I try to navigate to any other web page that Firefox slows down to the point that it takes two minutes for any page to load.

I created a symlink for Chrome's User Data and Chrome seems to be as responsive whether the user data is local or accessed via a symlink. What is Firefox doing that is so troublesome?