If the UCC Software policy contains packages that do not exist (moved out of repo, renamed etc.), univention-ucc-software-update tries to install them (apt-get update and apt-get install needed which takes time). In addition to the check for a needed update/installation, univention-ucc-software-update should verify that the package actually exist.
Fixed in r47895 univention-corporate-client 1.0.24-5.83.201402181608 r47897 2014-02-18-univention-corporate-client.yaml
Ok, non-existing packages are now quickly skipped.
http://errata.univention.de/ucc/1.0/31.html