To be more precise, in the case where a player downloads Diablo III or is patching Diablo III and starts playing it as soon as it becomes "Playable", but well before it hits "Optimal", does Diablo III continue to download patches during gameplay?
Diablo – Does Diablo III continue to download patches during gameplay
diablo-3
Best Answer
No it's already finished downloading everything. This is from their website:
Optimization
Obviously it doesn't always require that much space/consolidate that much some patches don't optimize anything.