Editor randomly running into memory errors

Version: Custom Nvidia Gameworks source build of 4.15

Specs: GTX 980, 16 Gigs RAM, Intel I5, Windows 10

Maybe this is expected, but while editing my open world environment(mostly while sculpting or painting the terrain) I’m continually getting random memory-related crashes. I have 16 gigs RAM which is barely used until Unreal starts up and it shoots up to 90%-100%.

I have 16 2048x2048 terrains, around 20,000 actors, and 1 million+ foliage instances, all split up into 40 streaming levels. It doesn’t seem excessive, especially for an open world, and I’m assuming Unreal has been optimized for these types of games, so the issue looks to be a memory leak.

I’m also using distance field shadows and texture streaming.

Any help diagnosing the issue would be hugely appreciated!

Forgot to mention that the framerate in the editor is fine, 60-80 FPS on average even with the long render distance.