Re: bhyve/nmdm/cu console paste in problem

I presume bhyve emulates a serial device, has a limited buffer and
can only work so fast before dropping characters....

Your best bet may be to use picocom or some such term emulator
program with a builtin support for "file transfer" or can use
an external program such as sz/rz which are designed to deal with
lossy serial lines. Put your "paste" in a host file and xfer it.
Alternately add another emulated net port and ssh in (if you are
debugging networking, this may require some ingenuity!).