The Upfront editor either takes a very long time to load or won't at all

The Upfront editor either takes a very long time to load or will crash my browser and not load at all on two of my sites. The websites in question were recently moved from GoDaddy to Bluehost ... several other sites were migrated as well but are not facing the same issue.

One site seems to slow significantly when I add an image on top of a section with an image background and then try to change the image properties/settings. The other site already has images setup in this same fashion, but it just now started becoming an issue with not being able to load Upfront.