We also are having this problem using a 4k monitor with macbook pros.
Same problem. Been reading the Adobe forums for suggestions for hours. Nothing works. No real time playback no matter what I try.
If someone from Adobe STAFF could reply with some news, that'd be great.
El Capitan 10.11.2
Mac Pro (mid 2010)
2 x 2.4 GHz Quad Core Intel Xenon
ATI Radeon HD 5770 1024MB
The core of the problem is that AE CC 2015 is having a hard time redrawing under El Capitan which is killing performance. I noticed it is way worse when on a retina/HiDPI screen such as a 4k monitor, or the 5k iMac. The reason for that is it is being ask to draw even more pixels. I am not sure when Adobe will get this fixed, but one workaround to help a little is to get info on the “Adobe After Effects CC 2015.app” and if you have a HiDPI display a checkbox appears that says “Open in low resolution”. Checking it gives you less pixels to push. Try it and see if it helps a little until Adobe fixes it properly. I think 2014 does not have this bug, so the other thing you can do is load it side by side with 2015 and use it in the mean time since the project files are compatible.
I've seen a few other people mention the UI causing the problem. Makes sense. I don't have a box that offers "Open in low resolution" so my solution is to revert to After Effects 2014. I run a very busy shop, so we don't have a lot of downtime for figuring out work-arounds for bugs. The new options for previewing are awesome, but without real time playback, After Effects is unusable.
On another thread, someone suggested previewing in Full Screen. That seems to work somewhat.
For anyone else coming to this thread:
To get real time previews, try putting the composition window in full screen.
Do this by hitting the tilde key "`"
This solos the composition window, which I guess (as James points out) lessens the load on After Effects having to redraw all the UI elements
If that doesn't work, I suggest reverting to AE 2014
The Adobe forums have been a useful source of information. Here are some other helpful links and info I came across:
HOW TO FIND AND INSTALL OLD VERSION OF ADOBE APPS:
ALL ABOUT PREVIEWS IN AFTER EFFECTS 13.x
FEATURES NOT AVAILABLE IN AFTER EFFECTS
http://blogs.adobe.com/aftereffects/2015/06/features-not-available-in-after-effects-cc-201 5-13-5.html (an older post, but some of these issues linger)
...Additionally if (like me) you are having issues keeping the Creative Cloud app running (i.e.: spinning blue gear or blank white box), here's some info about that:
1 Close the Creative Cloud application if it's running.
2 Navigate to the OOBE folder.
3 Windows: [System drive]:\Users\[username]\AppData\Local\Adobe\OOBE
4 Mac OS: /User/<username>/Library/Application Support/Adobe/OOBE folder
5 Rename the opm.db file to opm_old.db
6 Restart computer / Launch Creative Cloud
If you need to install Adobe apps manually, go here: http://prodesigntools.com/adobe-cc-2015-updates-links-mac.html
Adobe; bringing back the fun of using a computer in the 90s
I'm in the exact same boat. If I could get back all the time I've spent rebooting a crashed after effects session, horrendous playback, and "guessing" at where things are hitting with the audio, I might actually get some sleep tonight instead of working on this project...
I get this to on a MacBook Pro that has a 4K monitor. It is due to some redraw issues in 10.11 that are worse when you push more pixels. It is more bearable if you get info on the AE app and set the checkbox to "open in low resolution". But it is still not as good as it should be. It is the bug that I most want fixed.
Sent from my iPad
Pressing the grave key (`) over the composition panel to make it full screen, as mentioned, is the best workaround for this problem until the next update to AE where the fix is targeted. Here's info: Re: After Effects 2015 won't preview in real time after El Capitan update.
Metal API. Apple has introduced a proprietary shading language in El Capitan that may perform better than Open GL on a Mac. After Effects does not currently support Metal and may be causing redraw issues and crashing.
"open in low resolution" made a huge improvement. Thanks!
Try adding the render cue to the workspace then position it below the timeline and make it as thin horizontally as possible. If I do that even my Mac Mini will run real time previews.