Th thread evolved cuz we talked about it. At the beginning thinking it was linked to safari cuz many people are using it on a mac, and web browsing is the main activity for most users. So indeed, it has more chances to happen on safari, obviously.
We made some tests, clean install, combo updates, beta testing, flash or not, and noticed the freezing can occurs doing many thing and not only web browsing.
Macs, like iPhones, do not have all the exact same parts. A same component can be built by 2 or 3 different companies and have different versions, like the SSD, or displays, chips. That can be the reason why there is some freezing on some computers while others don't when a driver comes out.
At work, I've got a macbook pro 13 2010 running fine on El Capitan 10.11.4. But for some reasons, my MBP 13 Retina 2015 is freezing randomly on 10.11.4. No problems when ghosting to 10.11.3 with SuperDuper.
The most annoying part in here from some guys is thinking (like Apple usually does) the problem is not related to Apple but users.