mod_dav_svn performance

We've just completed a migration from CVS to SVN, with the new
repository hosted on the same machine, same filesystem, and provided
by way of mod_dav_svn to our users. What we're seeing is some nasty
divergence of performance; SVN is taking on average twice the time to
check out source. Is there any guidance available on improving the
performance of the server? We cannot justify throwing additional
hardware at the problem at this time, so a software solution would be
preferred.

Any suggestions?