In the Mixer item, under Sound in KControl, you can set various options for KMix:
Save the current sound settings to load later.
Load sound settings which were previously saved.
Automatically load the previous settings when you start KDE.
How many different soundcards KMix should look for when starting. Set this low to speed up KMix's startup time.
How many devices to look for per soundcard. Again, set this low to speed up KMix.