Dolphin needs to always open in background for speed up opening new window . File Manager is an importan part of any operation system and opening new window speed , is very effective . in Windows OS , WindowsExplorer is a part of explorer.exe and keep always open the app and whene user opens the WindowsExplorer , just a new window is created which is very fast . i think the speed of Dolphin in KDE needs improvement and this method can work for be effective .