Specific hitch after editing landscape in 5.1

Hi all,

I have a landscape, it is the max size with world partition enabled. The heightmap was imported from a 4.27 project. There is some foliage but I have removed it for issue debugging.

The specific UE version is 5.1.0-23058290+++UE5+Release-5.1. I am on Windows 10 with an Nvidia 1080ti, Ryzen 7, and an SSD on which the project is located. Not great, not terrible.

What I see is that if I edit the landscape, after every single operation, no matter how long or short the brush stroke, or the tool selected, it takes 4-5s for the editor to unfreeze. Undoing does the same thing. This issue was not always there (within this project, in the last few days), so there is something that has changed which is causing this hitch. You can imagine this doesn’t leave a lot of room for experimentation or less than fully opaque brush strokes because the editor just isn’t realtime at that point.

I thought it might be foliage, so I erased my foliage and that didn’t resolve the issue. I unloaded all world partition (this is a separate issue - my world partition details box looks flipped left to right, and doesn’t unload the terrain, only any objects that are located there - it seems disconnected from the landscape streaming proxy actors).

Is there a checklist of things I can look into to see why this is happening? I have seen it perform better, so there must be something I can change. Any assistance would be appreciated.


Just wanted to follow up.

I have tried a number of things, including unloading chunks of the landscape (which doesn’t work - unloading regions doesn’t actually hide that part of the landscape).

I found some success in disabling Edit Layers, which another user mentioned. That improved landscape editability but didn’t stop the random hitching.

I’m sitting in my editor right now at about 3GB ram used by UE, 60% ram used total in the system, and if I just spin the camera I can’t make it 360 degrees around without getting hit with a 4-5s hitch. I can’t lift my left mouse click or it hitches as well. When it hitches, it loses some info about what I was doing - it may trigger a right click context window or teleport me to a random place on the map (could be tens of km away - outside clip range so I need to zoom on something to get back to my map).

I tried giving up and exporting the heightmap to edit elsewhere. This generates a few dozen small images which I can’t do anything with without I guess a special program.

At this time I am 100% impeded, I am not sure how to continue exploring landscape creation with this performance issue. Does anyone have any recommendations? Are there any logs I can view which show what it’s doing for that 4-5s? It feels almost like it’s dumping something very large to disk but I don’t know why it would do that without editing, just spinning the camera.

Any assistance would be appreciated.