I've been having the same issue, mostly at larger airports. Has happened to me at both Inbuilds JFK and LAX on multiple occasions. All in game graphic settings are set to low, with both ground air traffic disabled. It doesn't happen consistently, but when it does happen it becomes much more frequent. Restarting or starring a different flight doesn't help. Only way I've found to reduce the occurrence is to completely restart the Xbox. I did LAX-LHR last night and had a memory error while in walk around mode at LAX. After restarting the consol and the flight, I felt like I had to be extremely careful while taxiing or panning the camera because I was afraid any rapid movements during an instance of lag would cause a memory issue. I turned off RAAS and didn't have any charts up on the EFB and felt like that helped a little.