Discreet or Integrated GPU

I have a late 2012 iMac with a NVIDIA GeForce GT 640M 512 MB. WoW has worked great on this machine since I bought it in 2013 for $1030 with no tax (on a military post). Since BfA install/launch, it has slowed down considerably, and not just with the game. It has slowed down period.

I thought about adding more RAM (I have 8GB), hearing that iMacs with integrated graphics share memory with the graphics. I looked into it and couldn't figure out how to tell if it had integrated graphics... the instructions I found specified to "look at the About This Mac settings." Well, all I see is the NVIDIA, but nothing indicating discreet or integrated... so after searching deeper, it "appears" that this is not integrated. Is this a proper assumption?

Anyway, I really don't want to buy a new machine, but I may have to. I did find this on Craigslist, but I'm not sure if I want to bite.

https://washingtondc.craigslist.org/nva/sys/d/apple-mac-pro-late-2013/6732953504.html
The 640M is a dedicated GPU but it is well below the minimum system requirements for BfA.

The second hand Mac Pro would probably fare a little better, but only barely. I believe the D500 is still below minimum spec, and remember you'd also need to purchase an external monitor with the Mac Pro.

If you can afford it, there are a lot of refurb 27" 2017 iMacs on the Apple Store with more up-to-date GPUs (the Radeon Pro 575 and Radeon Pro 580) starting at around $1600.
Thanks. I may wait around for the new iMac announcement this year. I'm hoping for some upgrades. I was thinking about the iMac Pro (lower end), but if the newer iMacs are "beefy" enough, I may get a top-end one of them. If I'm going to splurge on another Mac, I really want t o splurge (within reason).

My Macbook Air plays current WoW better off an SD card than my iMac.
I backup up my files and completely restored my iMac. WoW runs a bit better than before, but not much. The machine does run better aside from the game.
No new iMac announcement today, unfortunately.

However, if your iMac has the NVIDIA GeForce GT 640M 512 MB then it has both an integrated (intel gpu) and discrete card (the NVidia.)

The newer Macs (2017 and later) support external GPU enclosures.

I can play WoW on full screen on a 2017 i7 iMac at quality 8 pretty well. I get a little jerkiness at 10. Haven't raided on those settings yet, however, since it's at work and I'm not often at work during raid hours.

I do have to adjust the resolution down in the settings. It gets like 3fps at 5k resolution. I knock it down to about 2640x1560.