Mines mid 2012 13" MacBook Pro not even retina. Has a disc drive! It feels very sluggish and batt is horrible. This is my second Apple laptop and both seemed to become slow snails so quickly. I don't know if I'll buy another one again. My iPad 2 and iPhone 6 do everything I need it to pretty much.
I have a mid 2012 15" macbook pro non-retina. Buy an SSD with a clean install of OS X, and replace the battery. It will be like a whole new computer. I put an SSD in mine and it's fast enough I can't see any reason to upgrade it for another couple years.