I’m putting this here because it will help me remember to make this change everytime, given this is now classified as ‘WONTFIX’

http://betanews.com/2015/08/15/firefox-stealthily-loads-webpages-when-you-hover-over-links-heres-how-to-stop-it/

about:config
network.http.speculative-parallel-limit
0 

I found out about this from the patchmanagement.org mailing list: http://patchmanagement.org/