Debug tags in FreeBSD

[O. Hartmann]

Dear Sirs.
Sometimes I watch compiling 'world' or 'kernel' and recognize some '-g' 
options while compiling, especially when doing so with a FreeBSD 
5.X-STABLE branch.
Are all pre-releases of FreeBSD due to development and bug tracking 
'tagged' with debugger options and do they go away with a 'RELEASE' (or 
is this simply a stupid rumor that all STABLE versions are still tagged 
to be debugged)?

The reason why I ask is simple. I need my FreeBSD box for scientific 
researches and would like to squeeze out as much power as possible and 
therefor debugging options are meant to slow down code.

I'm not a development thug, so if this question sound stupid, I would 
regret bothering you. Hope someone will answer.

Thanks,
Oliver