As a mapmaker, I certainly won't be uninstalling Mapsource. When testing maps it's necessary to quit and restart the program frequently as changes are made. Mapsource starts instantly - no "database" to load every time. :p
Buy a quad-core machine with 16GB of RAM and that .NET application will start in no-time :D
It is not a problem of PC, it is a bad design of BaseCamp.
Well my comment wasn't a serious one :p I thought that was obvious...
On the plus side MapSource is still available and still usable--even with newer models if one cares to learn how.
MapSource is my primary Garmin utility. Although I use BaseCamp on occasions I import GDB files (from MapSource) or GPX files (from my devices). In short if you don't like BaseCamp continue to use MapSource.