Was this before FreeBSD 6? If I remember correctly smp wasn’t fully cooked in before that. Every smp system back then I used Linux cause yah know. Linux.
I started with FreeBSD with 5.4 while 5.0 was the first FreeBSD version with SMP support. I recall that I moved to 6.0 quite fast without touching the 5.5.
I have a screenshot from 2006/07 with FreeBSD 6.1-STABLE ... so I would suspect that it rather was 6.x series.