For several months it's seemed as though there was a ceiling on the number of visitors my site was getting and the number of page views. I'd get 27,000 or 28,000 page views a day, but never broke the 30,000 number to get to where I was last year. Visitor counts also seem to have hit a ceiling.
Back in August an advertiser of mine had me put an OTP ad on the site. If floated an animated ad with a talking sponsor for about a minute. It showed just once for a new visitor, and had a cookie set for a couple of weeks.
It definitely affected load time, and I have no doubt affected the number of page views.
The ad was dropped on December 31st and a week later I saw visitor count and page views rise. The rise over the past several days has been dramatic. The graph looks great.
Some of this I attribute to user behavior, but there's also signs that Google's page speed calculation was a factor.
Just an FYI.