If you want to speed up the sourdough bread, there are a few things that you can do. -Increase the starter percentage. Unless your sourdough starter is very sour, you can easily raise its percentage to 30 percent. Especially when you are looking for quick bread with quick fermentation. -Use a proofing box to proof the sourdough bread fast if you live in colder regions. -You can use a pinch of commercial yeast in the dough.