First off, sorry for my real bad english.
My Problem: Everytime i open a BP in Editor it “costs” Ram around 200MB. Thats normal, ok. Now when I close the BP-Editor the RAM usage stays exactly the same. If i open the Editor for exact that BP again, it “costs” no to nearly no ( 2 to 5MB) RAM. If i open another BP in Editor Excatly the same. First open (200MB) close it, RAM Usage stays the same, reopen (2 to 5 MB). Thats not very bad in small projects, but atm im working on something with a few more BP and when i opend too much of them, my RAM runs full ( 16GB) and UE4 crashes.
Anything i do wrong is this wanted or is it a bug for real 
Hi M. H.,
This is because those BP actors are not “loaded” when you launch your project. It is loaded after you open a BP, open a level with the BP in it, or open an asset referencing the BP.
This is expected.
-.
But shouldn`t they “unload” when i close them, “releasing” the Ram they use?
When you have assets that are rather large and take a long time to load, you don’t want to re-load it every time you open the asset.
The 200MB spike appears to mostly be the BP editor itself. Subsequent BPs opened tend to take up much less RAM, but ultimately the RAM taken up by BPs is dependent on the assets that they reference.
NOTE: This is only for the editor, actors can be unloaded during gameplay.