i attach static meshes to actor at runtime from code using code from wiki
AssetSM_StaticMesh = LoadStaticMeshFromPath(FName(*ModelName));
StaticMesh = NewObject<UStaticMeshComponent>(this);
StaticMesh->SetStaticMesh(AssetSM_StaticMesh);
StaticMesh->SetVisibility(true, true);
StaticMesh->RegisterComponent();
StaticMesh->AttachTo(RootComponent);
but this freezes game at 1 - 2 seconds. mesh is very simple have 200 triangles and one simple material with base and normal textures their size 1024х1024.