ETW Loading Times
From TWC Wiki
This page is meant to serve as a collection of tips allowing you to speed up loading times when testing mods.
Disabling Sound Packs
In preferences.empire_script.txt you'll find this line:
enable_sound true; # enable_sound <bool>, enables all audio content (default = true). If disabled none of the database or sound pack files are loaded.
As the comment says, the whole sound packs won't be loaded on game start, if you set this to 'false'. This option has nothing to do with the checkboxes in the in-game menus.