Optimizing My Game

I have been working on my first game for couple of years now and i have the map pretty much finished i have around 3500 textures and 2000 static mesh in total the map is based on a school so its not a large open world game but school blocks, classrooms,offices ect. In editor im getting decent frames at around 50fps and when i tested a launch with level streaming it loaded fine and played fine in epic settings other then some over budget hitching which was about 2000mb i removed this by deleting all folliage as i was testing with the new 5.1 and just painted over 300k of grass. I was looking at the matrix demo to compare my own game to and using stat unit and stat gpu my numbers are about the same if not better i noticed they use blueprints as all their assets are made up of packaged levels but being open world you have these blueprints placed over and over but my game being a small map with every class room a different size/shape i tried to packaged each classroom seperetly for example F1,F2,Canteen,Sportshall ect. As i belived this instances assets such as i have a building made up of say 200 assets but when packaged into a level it instances them into 1 instance in the blueprint. The problem i have now is when i try to launch the editor it crashes as my gpu memory hits 25.5gb out of 26gb and my dedicated memory is always 9.2 out of 10gb. My goal is to understand how to lower the gpu memory so i can load the editor without crashing and how to lower my dedicated memory as when i launch the matrix demo i am only using 6gb yet compared to my game the matrix demo is far more complex. I belive the editor crashes because its trying to load everything at once all my assets are nanite with the highest being aroung 5 mill nanited triangles.