I'm using Safari Version 10.1 (12603.1.30.0.34)
OS X Sierra 10.12.4 (16E195)
MacBook Pro 15" mid 2015
It only freezes that tab, if I close that then the rest of the browser is ok.
I've tried immediately closing whatever ad I see on the page, if I'm fast enough I don't get the freeze.
Here's a screenshot: