FreeBSD 5.X/AMD64: Linuxulator 64/32 Bit?

[O. Hartmann]

Hello,
I have a simple, maybe obsolete, question.
In kernel config templates (GENERIC) for FreeBSD 5.3/AMD64 I found some
compatibility options, namely

options         COMPAT_LINUX32
options         COMPAT_IA32
(options         COMPAT_43)

The system I wish to setup is a Athlon64 3200+ system. Software is to be
compiled when needed as it comes out of the ports collection.

If I avoid the above mentioned compatibility options, is the Linuxulator 
in AMD64-FreeBSD
64Bit like x86_64 Linux?

Assumed, I will enable IA32 compatibility, has this some performance 
penalties to a system running
nativ 64Bit software?

My intention is to avoid 32Bit software if possible (for simple testing 
purposes).

Thanks.
Oliver