Strange, I got a notification about Jiffy posting to this thread, but that post seems gone???
Anyway, InkThemes have released a new BackBird version. It went from 1.0 to 1.1. Here's my findings:
Version 1.1 correctly fixes the one line of code that was responsible for the bug this forum topic is about. However, it DOES NOT FIX any of the bugs mentioned by songdogtech above, dispite songdogtech's clear instructions what to do about them, and contrary to their report that they have fix them. We still have missing files resulting in 404 errors (another source of considerable page load slowdowns), as well as more W3C errors.
Now I could close this thread and start a new one on the other bugs, or re-raise the issue right here. Either way the aftertaste remains unpleasant. InkThemes call their themes "professional", but repeatedly fail to do their basic quality assurance homework in order to rightfully deserve that attribute (even when instructed how to do that homework).