I mean does one need to update to this version to remain security safe/ Or is this update merely a performance improvement?
This is a stability/functionality update. Full details can be found here: http://helpx.adobe.com/flash-player/release-note/enduser-release-notes-11_3.html
So if one is not having an issue with the flash player that came out just before this release, then it is ok to not upgrade? I mean one would still be as safe security wise?
Yes, that is correct.
Retrieving data ...