You will want to convert it over to Hierarchical Instanced Static Meshes so that you can take advantage of LOD’s. I have done that with mine already. You also need to save in a custom struct the array information so that when you reload it still exists, otherwise once the construction script runs they will all get destroyed.
All the interactive objects in mine remain as regular actor blueprints rather than converting them to instances, but i suppose if you have thousands of them then using an instanced mesh and converting it back once the player gets in range this could speed things up a bit