I got Macbook retina with Nvidia 750, 16gb ram....Yosemite 10.10.5
I did fresh install of CC 2015, and After effects is very laggy! Every 5-6 seconds it freezes for 2 secs - same with interface, going trough menus, working on comp.....
All other CC apps works fine, the only one with performance issue is After Effects.
I was trying to search on Google, but looks like there are no similar problems with After Effects (the only similar problem was with Photoshop with some users...)
That sounds frustrating. Most people I know who use CC 2015 on Yosemite aren't experiencing that issue.
When you did the fresh install, had you ever had AE installed before? If so, did you run the CC Cleaner tool from Adobe before you did the clean install?
I'd recommend that you file a bug report: Feature Request/Bug Report Form
In the meantime, try using CC 2014 and see if it behaves properly: How to Find and Install Previous Version of Adobe Apps in CC 2015 |