Constant memory crash

Getting constant memory crashes, especially in Northrend, and almost always taking a flight path.

I tried googling, people say get the old client. But the old & new client are the same now? There is now patch-x.MPQ file in my WoW.

Trying to download the client again I see the new and old are same thing??? Unless they all have the same files now but they are different?

Yes, new and old ones are the same.
Is it caused by an addon maybe? Try disabling addons or try https://www.techpowerup.com/forums/t...-aware.112556/
Some users said that the "Large Address Aware" fixed issues for them.