After upgrading to 12.10 my system slowed down considerably. how can i make a new installation from scratch without loosing my adjustments? i have a dualboot system and a partition with all my personal files and data.
If the separate partition with all your personal data is a separate /home partition (recommended) then all or most of your settings will not be overwritten. To restore installed programs you can make a list with dpkg --get selections and re-install them on the new setup. Have a look at the answers to this question for a few different methods to do this, but I recommend the dpkg one if the system is the same release level.