I wish adsense would just find a way to make those living in the U.S click ads
Click-through rates for U.S. visitors are above-average in my account, so it's not true that "U.S traffic hardly clicks ads." Apparently, they click less
on your site(s). Perhaps the ads targeted to U.S. visitors
on your site aren't as interesting. I see the same in my account, but then with countries like India, Indonesia, Japan and Mexico, where the CTR is about 1/3 of the U.S. CTR.
Nearly half of all visitors will leave a mobile site if the pages don't load within 3 seconds
You'll want to make sure your content loads (well) within that timeframe; it's mostly about "DOMContentLoaded", not so much the full load time. The ads will be loaded asynchronously, so they shouldn't interfere with the user experience, unless, as I've seen on too many sites, loading the ads causes the content to jump around (while I'm reading) to make room for them.
November is performing very well for me. RPM is up by about 30% compared to last month.