The MIX elements in EMGD are sub-optimal with modern systems as GStreamer has decent VA-API support now. These should be packaged separately so distributions can opt out of them and use gstreamer-va from GStreamer.
I think this may be a duplicate of: [Bug 2551] EMGD requires video acceleration but not entirely sure, so won't mark it as such yet.
The fix for 2551 would also package the MIX elements separately, so marking this as a duplicate. *** This bug has been marked as a duplicate of bug 2551 ***