Do I need a new wetsuit or not?

I have an entry level Xterra Vortex from 3 years ago. It has a few cuts in it but no all the way rips, etc. I lost about 15lbs since I first go it so I probably could go down a size. Will it make that much of difference if this is a size too big and with the cuts?

In warmth, probably not. In performance, yes.