On Wed, 29 Jun 2016 13:17:59 -0700, David E. Ross wrote:

Post your question (and any other Firefox qeustions) to the
mozilla.support.firefox newsgroup on the news.mozilla.org news server.
Accounts at news.mozilla.org are free and quite easy to setup.

This might be bug #705483 at
https://bugzilla.mozilla.org/show_bug.cgi?id=705483. If not, consider
submitting a new bug report. The product would be Core; the component
would be Networking.

I did post the question there.

They told me firefox has nothing to do with HOSTS lookups
(which is essentially bad information because firefox
caches old lookups in its own dns cache).

They did suggest the 30 steps here to stop Firefox
from connecting to rogue web sites:

How to stop Firefox from making rogue connections
https://support.mozilla.org/en-US/kb...ic-connections