The speed scores from the Go Daddy Pro utility shown above are with the Sirv plugin off. The time before, the grade was A in both categories. Notice how much slower the site is without the Sirv plugin enabled.
The Sirv plugin has been set to not serve the images from the Sirv CDN because the feature images in a post list are not displaying. We use a post list on the home page.
There seems to be some extra weirdness in how ThriveThemes delivers the images with its framework.
The developers are looking into it.