In unreal 5.4.2 Manipulating splines is super slow. Is there a fix for this or? is there something to optimize this a bit? This seems to happen with or without meshes attached to the splines but far worse with meshes.
Try to unload parts of the landscape streaming proxy (if it’s set up with world partition)… that can help with how the spline affects the landscape deform.
Other thing… if you have meshes attached, try to have simple collision to them, check that I had a problem like that in a project I am working on…