I was just editing, selecting meshes, the file is 142mb, I don’t know what happened there, I guess the file is too big and cause may be some freezing?
Compiling shaders the first time takes a long time.
Vulkan should fix this.
I don’t know anything about that, but I was trying this
And the file I have edited closed up. It is a nice detailed model for the game engine, but a cube wouldn’t be the parent of the mesh, and it wouldn’t move, either way it eventually closed up. The vertice count for the edited file is 2,705,152 so adding in a detailed model like this would probably be a problem, a big problem. Right?
Even without, the file I edited went from 140mb to 344mb, and now I managed to keep it at 615mb. I was duplicating objects to create a scene, and i didn’t realise that one whole object is 15mb in the game environment. Hmm
Really nice detailed model, the person who made it even had a two hour record of it. I watched most of it, skiping parts of it.
I duplicated some objects, moved them nearby, saved the file and they aren’t there on opening the file again. I believe this happened two years ago with some objects, so I wasn’t sure what the cause of that was, nothing to do with the timeline or animation settings.
Here it returned back to its original position once opening. 
The objects were already on a frame, so that caused them to move when opening the file.
I found a problem, when the player goes up this area it gets stuck, I did try raising the ceiling mesh, a few times, but no change.
I thought about doing an edge loop in the middle
But, yeah may be it is the layout, one area the player can walk fine up the stair case, but in another part .
The program crashed while trying some edge loops.
The edge loops didn’t change anything.
It wasn’t the solid static covering the mesh all in one level layout. It couldn’t be since one area the player can walk fine. Could be the player has a slight weightlessness movement about it, that may be it gets stuck in the duration of the movement in some places.
I duplicated some objects and this occurred when I tested it. What are these black coloured rectangles?
The file got to over 1GB. I had to limit the amount of objects in the layer, using an empty to duplicate objects seems the best way to lower file size, went down to 707mb so far. 
I would bake the high res to a texture on a lower res. Get the detail with less verts. Those verts will kill the performance. Remember, noc are non hero assets, so low rez. Characters and full interactive noc is hero. These can be a little more rez. I found a balance of no more than 50k verts for heros is best. And 15k for non hero. All other things like buildings i would use lod of a baked out cube and only like 1k verts for high quality lod
I simply removed the objects that caused the file increase, and loaded them in as empty
I don’t know about anything more than AI, I just downloaded a few available on blendswap that have no restrictions, and I added my own. Everything is from somewhere else, just edited. 
I considered my own ai, but it wouldn’t be that exciting. The file is very small, the area, so I have to edit or remove to make it more workable beyond what I have tried so far.