UE doesn't use resources of PC

Hi there.
Looks like UE doesn’t use resources of PC properly. Processor, video used 6% and 20% during work. Landscapes looks weird with sharp edges, LOD loading very slow. Even to build new hills they have sharp edges and sometimes a plato on the top. While moving camera graphics loading.
Problem started 2 days ago, a week ago was building lvls with no problems in UE4 and UE5. Old objects in a project looks smooth, new ones with edges.
I’ll appreciate any help to solve this problem.