This absolutely does not mean 12,0000 times too much disk space has been used. Rather, it means 9,000 more bytes are being used than are, according to your theory, "necessary".
Why are you freaking out about less than 10K of disk space? PerlMonks would save far more disk space by deleting all the nodes you've posted, than by replacing <CODE></CODE> with <C>. (Not that I'm suggesting such a thing, of course. ;)
Aside from the fact that your proposal just wouldn't work, because all the occurences of > in the code would have to be encoded, which defeats the purpose of having such a tag in the first place.