Also running into the same issue as well as the Sorenson Squeeze EOL.
The way to go right now, from what I can tell, is Export file>Avid Media Processor or MXF OP1. Either one outputs an MXF file with your choice of DnxHR flavor. Not quite as quick as a QT reference, but it’s much quicker than exporting a quicktime. For example, exporting a 20-minute sequence on my machine, 4K DnxHR in quicktime, was taking over an hour. Exporting an MXF takes less than 15 minutes.
The only problem I’ve encountered is that squeeze can’t read these DnxHR MXF files.
The one issue that’s keeping me from going to AME entirely is that it can’t link separate video and audio sources. I’m often delivering a video with multiple languages and audio versions, so it’s a huge timesaver to only have to export one video track, and create multiple audio versions with Squeeze.