It’s ridiculously over spaced by default, and in addition to correcting this, you may want to reduce the font size to get that extra half page you desperately need to eke out to meet the page limit.
To accomplish these two goals, put the following in your preamble:
\renewcommand{\IEEEbibitemsep}{0pt plus 2pt}
\makeatletter
\IEEEtriggercmd{\reset@font\normalfont\footnotesize}
\makeatother
\IEEEtriggeratref{1}
I know just slightly more than exactly enough to get myself in trouble, so caveat utilitor.