Originally Posted by theredben
Not to split hairs, but under-oxygenating actually decreases lag time. The yeast reproduce until they run out of oxygen. Fermentation begins when oxygen ends (sort of).
Yes and no.
Not enough oxygen can lead to extremely long lag time as reproduction is slower and can lead to a stalled fermentation. They NEED that reproducing time.
On the other hand, over oxygenating has it's own issues. (Meaning adding to much pure O2).
Also, stressing the yeast can influence flavor, as can under pitching. (Trappist beers for example, are well oxygenated & under pitched).
Danstar used to have a pretty good FAQ on all this.