Not much, not at combat distances. Supposedly the rule of thumb is 50 fps per half inch of barrel (I think).
Still, there is newer ammunition optimized for shorter barrels (faster burning powders.
I think in a K-frame the 4" barrel is the perfect balance, but for an N-frame the 5" is best. Oddly, they made the first in large quantities, but the second (in different calibers) was not made much.