I am trying to nail down a memory leak that has appeared again. So after, lets say, 6-8 hours of a flight, should the fs9.exe process be at memory usage of over a gigabit? that must be a memory leak, right?

A little over a gig with the PMDG 747 is not all that unusual. Mine would crash at around 1.6Gb. Is your memory leak causing a CTD with no error message? Then change all the MaskClassMap=3 & =1 to =0 in the terrain.cfg file. If you're getting the OOM error message during a CTD then start troubleshooting landclass add-ons and/or bad/duplicate AFCAD's. Good luck....

Thanks for the reply. I get a CTD with the out of memory error, I do not have duplicate afcads but I am still hunting for some type of errors...

Oddly enough, landclass in the wrong type of directory can cause memory leaks. Make sure all landclass files are in a directory or directories that only have a scenery folder and no texture folder.Lee