This is a solution if
-You try to load the game (vanilla or DarthMod) and you anticipate "CTD or endless waiting" at game start.
-You notice lag during battles. This can be caused when you change GFX settings in the game (for example unit size, Unit Detail etc.) and you save. The game preferences file may get corrupted and so you have to reset it correctly with the following procedure.
Step1
Press the button "DISABLE TO PLAY VANILLA" of the launcher.
Step2
Re-start Steam.
Step3
Load the game as Vanilla, change any GFX settings, close.
Step4
Next time you can enable and play DarthMod.
(NOT NECESSARY any more but I leave this for a hint should the above mentioned does not work)