PXE image slow to load boot.wim when using UEFI

PXE works great with legacy boot options, but when booting with BIOS set up for UEFI, it takes a crazy amount of time to PXE boot.  

Attached is a screenshot showing attempted boot after 5 minutes at which point I had to give up and move on to something else.

I'm on 8.0 HF6.  I see there are some DS related point fixes available for HF6 here but don't see anything like this mentioned.  Support suggest we don't get to 8.1 yet.

Anyone have any ideas?  I've seen the slow boot with a VMware created image and a Dell XPS as well.