The more you say the longer it will take to figure out what your asking to be done in my experience. I have AIVC installed and it does not effect how S voice works. Its far from Siri if thats what your after!
AIVC is what I was referring to mainly outbreak47, but hell, the stock "voice search" app will work faster in terms of calling,texting or searching but its not all that great...but deffinately faster...
Basically the recording "blue tone" stays active for approx 2 seconds after Im done speaking. If Im asking for a "call somone" or "text somone" command it takes about 2-3 seconds on average of "green tone" before fullfilling the command. If Im rambling on for a length of time for an obvious internet search it can take 4-6 seconds before giving me the reponse to search the internet. If your experienceing longer delays try an area with a better 4g signal. If that doesnt seem to be the case there may be some issue with your N2...