How big can objects be

[Firstinaction]

I want to build a pretty big gun or cannon if I may... It will be pretty big and I have more details on it here in this thread - http://tremulous.net/forum/index.php?topic=14220.0
I have questions- -Will it be a good thing to have a big object just too look at and go inside it?... Will it slow down performence?.. 
UMMMMMM....  Will it be able to be in tremulous ( such a big object)
"Note that it wont be that big were its so huge its like big as a planet" Just saying...

Please answer back and plz dont flame me becuase of this... LOL

[CATAHA]

I think it can be VERY big. But it gonna hurt performance if detailed (or look crappy if not). =D
If you making tall building, for example, you can try use some optical illusion for it. Just well-calculated piramid and properly created texture. =)