To fix lag and rollbakcs in editor you need set the valors in SourceCode\You Engine Version\Engine\Config\BaseEngine.ini
[/Script/OnlineSubsystemSteam.SteamNetDriver]
NetConnectionClassName="OnlineSubsystemSteam.SteamNetConnection"
MaxClientRate=100000
MaxInternetClientRate=100000
[/Script/OnlineSubsystemUtils.IpNetDriver]
MaxClientRate=100000
MaxInternetClientRate=100000
[/Script/Engine.Player]
ConfiguredInternetSpeed=50000
ConfiguredLanSpeed=50000