After Effects CC 2015 was the beginning of a significant overhaul to the architecture of After Effects. The preview system as you know it from Ae CC 2014 (13.2) and previous has been completely reworked in Ae CC 2015 (13.5).
You should also know that preview has evolved a bit since 13.5. I think you should consider upgrading to the current release of Ae, 14.2.1. It is significantly more polished than 13.5 was, with a lot of new features, performance improvements and bug fixes.