Why is MySQL nearly twice as fast on Linux/AMD64 Vs. FreeBSD/AMD64?

[JG]

>I'd recommend replacing those 1GB modules with 4 512MB modules.  That
>should yeild improved performance across the board by giving both CPUs
>their own RAM.
>
>-- Brooks

Brooks,

There are only 6 ram slots available on this board, for us it makes more sense
to use the 1GB modules rather than the 512's. Before it goes into 
production I'll
be adding 2 more 1GB modules. But right now I am just trying to figure out what
OS it'll be on. I'm a FreeBSD guy so I've got my fingers crossed for some 
better
FreeBSD performance after I recompile.