8 hours to render a less than 1 GB video in H264?

This hasn't been a problem until ME & Premiere CC 2018, but rendering anything in H264, even with recommended presets for YouTube, Facebook, etc. is taking astronomically longer than before. Even when using almost all of my 16 GB of RAM, I've got an 8 hour render time on one video estimated at about 700 MB. Previously this would have taken maybe 1.5-2 hours max. I've got software that automatically dumps my caches and clears up RAM when needed, but it doesn't seem to have an effect on Media Encoder or Adobe.

Anyone have a work around other than encoding in Quicktime?

System:

  Model Name: MacBook Pro

  Processor Name: Intel Core i7

  Processor Speed: 2.2 GHz

  Number of Processors: 1

  Total Number of Cores: 4

  L2 Cache (per Core): 256 KB

  L3 Cache: 6 MB

  Memory: 16 GB