CS6, CC, CC2014 all load within 8-10 seconds.
CC 2015 takes 1:20 seconds on average to load.
I have no plugins installed.
This is a brand new SSD with fresh copy of Windows 10 and After Effects.
I even popped in another SSD and reformatted, installed Windows 10 and After Effects and still had the same issue.
First, make sure you have the latest build. Second purge your preferences. Also make sure that you have not changed the presets directory. You can test to find out of indexing effects and presets is slowing things down by closing the Effects and Presets panel and then restarting AE.