I built my wife's Company Web site with SMARTY 3.0.7 on PHP5 in 2012.
Last week the ISP upgraded its servers to PHP7 and the site bombed.
Upgrading to SMARTY 3.1.30 was easy and got the site back up ...
This site is built using Smarty 3.0.7 for my wifes business.
Sorry but most of the nice stuff is behind the scienes.
I realy like the new page based cache in 3.x