Slow access to ajax.googleapis.com

In the last couple of weeks, I have been experiencing problems using Firefox on my Mac. I've isolated that it occurs on calls to ajax.googleapis.com, webpages become very slow to load including some timing out entirely. It appears that other Apple users have also experienced this issue though typically with Safari. Like others I've tried removing plugins, emptying caches/cookies, etc and nothing helps. I have two Windows computers in the house that do not have this trouble. This also isn't happening when I use Safari from my Mac or use my iPad.

Does anyone have a solution suitable to a Mac (early 2009 model) using Yosemite and Firefox 42.0. Again, this does not occur when I use Safari from the same computer nor when using any other device besides my Mac desktop.

Thanks,

Amber