Effects of race mixing

[AFODO]

The soul always like the body, It always been like this, and built for that body, no matter what race, or sub-race.
Your idea of mixed people's souls are weaker, or "confused" is just not true, these souls always meant to be in that body and they are gentile. Again, their is soul built for their body, there is no confusion here.

Even if this effects the speed of advancement, you can't compare and mesure it, as the speed of advancment is mainly influenced by the person's situation, natal chart, and personality.