I put about 80 videos in a Comp in After effects. i want they all play the same time for 20 seconds. In Media Encoder it takes about 3 Hours to render that 20 Seconds. (yT 720p, AE CC 2015, AME CC 2015, Windows 10). How to fix that?
DOn't use AME to render the comps. Eender an intermediate file directly from AE and encode it later.
how to render an intermediate file direcly in ae?
Add it to the render queue and choose a good intermediate codec. Some people like QuickTime with the Photo JPEG codec.
Rendering is one of the very basic things you should know about AE. If you're unsure on how to do that, there's probably a TON of really useful information that you should know and it would eliminate a lot of your frustration! Go through these resources to get a basic understanding of AE: Getting started with After Effects