New environments that take up a lot less space than the original ones:

\newcommand{\backskip}{\vspace{-0.4\baselineskip}}
\newenvironment{compactitemize} % compact itemize list
{\backskip\begin{itemize}\itemsep0pt\parskip0pt}
{\end{itemize}\backskip}
\newenvironment{compactdescription} % compact description list
{\backskip\begin{itemize}\itemsep0pt\parskip0pt}
{\end{itemize}\backskip}
\newenvironment{compactenumerate} % compact enumerate list
{\backskip\begin{enumerate}\itemsep0pt\parskip0pt}
{\end{enumerate}\backskip}