32/64bits emulation questions.

Hello list.

Currently I am maintaining a project which compiles with the old Borland 
Turbo C++ tools (v3.1). I intend to move a full linux dev environment in 
the short term. I have been running some tests with dosemu with very 
promising outcomes, even allowing me to compile the full project through 
a gnu-makefile setup, running the compiler via dosemu -dumb.
These tests show a very nice performance in 32bits machines, but very 
poor in 64bits machines.
 From what I've read around there, I think this problem is due to dosemu 
emulating code instead of using CPU virtualization. As I didn't find too 
much in-depth info on this, I thought asking in the list would be a good 
idea:

* Is this true? Will dosemu use the CPU emulator instead of 
virtualization on x86-64? Or am I just plain wrong?
* Is there any know workaround for this issue? I recently found 
http://v86-64.sourceforge.net/ but really couldn't get it to compile 
under latest kernels.
* Would running dosemu under a 32bits (virtualbox) virtual machine be of 
any help to my purposes?

Regards and thank you all.
Pablo.