curious which source repo is more effecient in terms of using server resources, git or svn?
If you mean saving resources on your repository server, I would say DVCS in general (git, bzr, hg, etc.) are more efficient because there's more operations that can be done locally.
For example, with DVCS, you can easily merge branches on your development machine and then commit the result to the repository machine, while a centralized VCS (such as CVS or svn) will have to do the merge on the repository machine, thus using more resources on it.
When it comes to disk resources, I find git and bzr more efficient also because CVS and svn put versionning info at each level of the tree (CVS dirs in the case of CVS, .svn dirs in the case of svn) while git and bzr use only one directory (.git or .bzr) at the top of the tree, which is more efficient in terms of disk space.