Double clicking a comp in the time line will cause a beach ball lock up 30-60sec.
Using any other method to navigate between precomps will load the precomp instantly (such as tab menu, right click menu, etc).
Even with nothing in the precomp, double clicking it will cause the beach ball.
OSX 10.10.5 Yosemite
2.7ghz 12 core
64 GB ram
Working local, no network
Tried on a fresh precomp, same thing
That's really odd. I don't have a machine with Yosemite to test, but my El Capitan machine (running the same version of AE) isn't having that problem. Do you have any other computers you can test with?