File manager time to run --- why are some very slow?

Some file managers open very slow on kubuntu, bullseye 11. I had a problem on UDisks2VolumeMonitor, so fixing this, halved the time needed to run. (ps. UDisks2VolumeMonitor --> problem on mraid2 not fixed) fixed by applying some of these: sudo apt-get install appmenu-gtk2-module chmod +x /usr/libexec/gvfs-gphoto2-volume-monitor sudo apt install --reinstall glib2 -y sudo apt install --reinstall gsettings-desktop-schemas fixing XDG_DATA_DIRS paths references: Do you have overlay scrollbars activated? If yes, take a look at this bug report: https://bugs.launchpad.net/ubuntu/+source/xfce4-settings/+bug/1239014 https://gitlab.gnome.org/GNOME/gvfs/-/issues/541 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=950174 So i measured the time these file managers need to run on my system: Dolphin and Krusader less than 10sec.. other more then 30sec. Note: I have 8 usb HDD on self-powered usb hub mounted. So i would like to trace why eg. Nautilus takes 1 while minute to run!!! How i can do this? Do you recommend any other file manager that can be faster (NOT Terminal based)? nemo Current gtk theme is not known to have nemo support (Adwaita), adding some... real 0m34.582s user 0m0.755s sys 0m0.036s after some changes / updates - no error on UDisks2VolumeMonitor Current gtk theme is not known to have nemo support (Adwaita), adding some... real 0m28.351s user 0m0.538s sys 0m0.048s Nautilus error StartServiceByName for rg.gtk.vfs.UDisks2VolumeMonitor: real 1m20.784s user 0m0.878s sys 0m0.072s after some changes / updates - no error on UDisks2VolumeMonitor real 0m55.335s user 0m0.642s sys 0m0.080s thunar error StartServiceByName for rg.gtk.vfs.UDisks2VolumeMonitor: real 0m54.789s user 0m0.465s sys 0m0.076s thunar after some changes / updates - no error on UDisks2VolumeMonitor real 0m29.717s user 0m0.523s sys 0m0.125s pcmanfm WARNING **: 10:19:01.112: XDG_TEMPLATES_DIR is set to invalid path, ignoring it error StartServiceByName for rg.gtk.vfs.UDisks2VolumeMonitor: real 0m52.694s user 0m0.250s sys 0m0.032s after some changes / updates - no error on UDisks2VolumeMonitor WARNING **: 10:19:01.112: XDG_TEMPLATES_DIR is set to invalid path, ignoring it real 0m27.530s user 0m0.410s sys 0m0.094s dolphin QApplication: invalid style override 'GTK+' passed, ignoring it. qt.qpa.xcb: QXcbConnection: XCB error: 5 (BadAtom), sequence: 628, resource id: 0, major code: 20 (GetProperty), minor code: 0 real 0m7.418s user 0m0.833s sys 0m0.091s QApplication: invalid style override 'GTK+' passed, ignoring it. qt.qpa.xcb: QXcbConnection: XCB error: 5 (BadAtom), sequence: 628, resource id: 0, major code: 20 (GetProperty), minor code: 0 real 0m2.385s user 0m0.708s sys 0m0.087s krusader NOT TESTED WITH UDisks2VolumeMonitor error warning default unknown@0 # QApplication: invalid style override 'GTK+' passed, ignoring it real 0m2.268s user 0m0.684s sys 0m0.207s