I saw more than a couple of sites have issues, including one of ours. They would hardly load at all.
Google itself was one of them. I traced it, in our case, to our use of the translate widget without calling it async (on the home page, no less). Needless to say, I fixed that ASAP.
I found it curious that I'd just read about this a couple months ago and then it crept in to bite me/others in the tuchis ...