This is the exact same problem in Apple's Motion when doing a preview.
It's the result of bad UI programming in which both Apple and Adobe have given various parts of the UI a too dominant thread, more so than the playback of the content. Which is, of course, ridiculous.
But that's what happens when product managers don't use their product, they don't prioritise for the end user experience because they have no idea what the priorities of the end user are...
unfortunately Adobe support chat was no help at all.
First of all, sorry for this frustrating lack of service from chat. For sure, ask to be connected to the "video queue" next time you try our chat service. Feel free to try the service again. If it does not work, you can opt for help over the phone. You can also send me a PM and I can set up a call back at your convenience. Let me know what you'd like to do.
When I press 0 on the num pad to preview it renders but plays in half speed, The problem seems to stop when I remove the timeline indicator visually from view... it's a very odd problem...
Slow preview, even after frames have been cached, seems to be a growing issue for Mac users since OS X 10.11 was released. Did you have the same issue with OS X 10.10?
Not that I remember, although I'd really rather not downgrade my whole machine for this unless I really ultimately have to.
Bootcamp & Windows 7 = a faster, more responsive AE in ye old Windows world.
Never in a million years.
I have bootcamp installed but it's not worth the hassle of migrating everything over, personally for me the workflow is so much better on Mac.