Do toasted nuts quickly lose flavor? There are many recipes where freshly toasted nuts are called for, and that got me wondering--how far can I toast them in advance without sacrificing flavor?  

If not, how quickly do they lose flavor, and what causes the degradation?  Are there any ways to store the nuts to preserve the flavor of freshly toasted?  Would freezing and/or vacuum sealing do the trick?
Toasted nuts keep their flavor pretty well, the way to keep them is the same way you'd buy them at the store, ie a sealed container. 

What you get from freshly toasting nuts is more aromatics than flavors. Most of the aromatics go pretty quick so there's no preserving them, it's use 'em or lose 'em. Could you substitute pre-toasted nuts? Sure, it won't be quite the same, but it will be close.