Yes me too. For me they are mostly:

• the useless start animation (it is not an overlay but just delays the system start)
• the panel, "icons only taskbar" using middleclick to spawn another window, while I want to close
• the sounds
• the touchpad not being "natural scrolling" · the system monitor not starting with the page didsplaying running programs, and having a warning message when closing an app (like, you only do this in edge cases where it might be time critical)
• set animation speed to fastest
• set Konsole, Dolphin and okular to always use tabs instead of windows (konsole needs a modded desktop entry for that)
• extend the screen lock duration, reduce the screen turnoff duration, remove the dim duration
• set power profiles to auto switch depending on charging state
• enable some effects, disable some others
• disable baloo at it is a crashy memory hog causing tons of trouble for reasons that dont make sense
• enable full tememitry
• disable the tiling editor and possible workspaces, to save resources?
• change keyboard shortcut for "print" to select rectagle selection in spectacle
• some different standard programs (like Gapless, SimpleScan and Celluloid instead of Elisa, Skanpage and Haruna/Dragonplayer)
• disable floating panel and adaptive opacity