We use a Project tool with a feature dataset (input) in order to do geographical transformation and have an enormous running time - days
We cannot do it per each feature class. See the link Project—Data Management toolbox | ArcGIS Desktop
We assume that the majority of the time spent to recreate geometric networks, relationship classes etc.
Probably, there is a "clever" way to transform data
First remove all networks, relationship classes etc.
Third, recreate all networks, relationship classes etc.
Any help will be greatly appreciated.
ArcGIS Desktop 10.5.0