When an Encore build is slow, you should separate the transcode of timeline assets from the rest of the build. And if using Encore for the transcoding, elect to use AME instead of Encore.
You have accomplished both these by following John's suggestion.
Within those first 15 minutes, you demonstrated that it really is a slow process. I would then test your workflow further by exporting only a short piece. You may get to the end and find that a) it crashes or b) once imported to Encore, it does not work, creates other errors, etc. So I would export a very short bit, bring that into Encore, and see if that will fly.
Exports can be very slow if there are effects applied that take a lot of time, or it is not using your GPU (or the effects were not CUDA enabled) or whatever. There are also choices regarding "Max Bit Depth" and "Max Render Quality." Those are all Premiere/AME issues.
Here's one search: