I have been using After Effects CS5.5 for personal projects for a few years and just started a trial of After Effects CC to evaluate it for professional use. I have imported a project I created in CS5.5 to compare to CC. My preview rendering performance seems a bit better, but final rendering performance with Media Encoder is abysmal and unacceptable for professional use.
The main project I'm using to benchmark is a 4 minute video with many layers, including plenty of nested compositions and PSDs. After Effects CS5.5 can render and encode the timeline as an h.264 MP4 in 15 minutes. Doing the same from CC using Media Encoder CC with the same settings takes 55 minutes.
In case the performance was related to the h.264 codec, I tried importing the previously rendered MP4 file by itself and rendering it back out as a WMV. This took 6 minutes in CS5.5, and 65 minutes with CC / AME (65 minutes to re-encode a single layer video with no effects?!)
Finally, I tried rendering the most complex 30 seconds of the original project so I could compare performance with CUDA on and off. CS5.5 took 3:51 (that's minutes and seconds) to render this section as an h.264. CC/AME took 8:20 to render it with Mercury CUDA turned on, and 9:33 to render it with CUDA turned off (software only).
It looks like best case, AME CC takes over twice as long to render as After Effects CS5.5, and in the worst case it takes 10x as long. If I monitor my system performance during the export process I can see that CS5.5 will use 100% of my CPU when rendering. However, when rendering with the Creative Cloud software, I'll see After Effects CC using 30-40% and AME using 5-10% with a total never exceeding 50% of my CPU power.
Neither AE CC nor AME CC seems to have any settings to control available cores or maximum CPU usage. Is there any way to convince AME to use more CPU power for faster rendering, or has Adobe just crippled our rendering performance with their latest software?
Windows 10 Home
MSI GTX 970
In AE CS 5.5 encoding to H.264 was done directly in AE but in the latest version of AE, you would have to send that composition to AME, for encoding to H.264. When AME is encoding AE composition it uses AE headless renderer to serve frames which in your case seems to be slower.
One other option is to render AE composition into a lossless format in AE and also have it render to a folder that is set up as a watched folder in AME. Set the encode preset to H.264 for that watched folder. See if that option is faster for you.