A small Ubuntu 13.04 virtual machine instance I run in a cloud environment regularly becomes slow/unresponsive because of a proces called check-new-release. Is there any way to disable this process and maybe run it manually instead?
apt-get remove ubuntu-release-upgrader-core
The script that you're seeing running is
/usr/lib/ubuntu-release-upgrader/check-new-release, and removing the above package will remove that script completely.
A description of this package is:
ubuntu-release-upgrader-core - manage release upgrades