Difficult though it may be, I have been trying to analyze my vocal production of this word, driving the lovely AnnaS up a wall in the process. I do purely believe that I am switching from a voiced sibilant to an unvoiced sibilant in mid-stream, making it something like painzstaking. Note that this does not imply any lengthening of the sibilant. I don't hear any interruption of any sort anywhere in the word.

YMMV