Newer versions of Kubuntu are missing the advanced mouse options which let you debounce the mouse
sudo apt install xserver-xorg-input-evdev
sudo mkdir -p /etc/X11/xorg.conf.d
Then edit /etc/X11/xorg.conf.d/xorg.conf
and append:
Section "InputClass"
Identifier "evdev-mouse"
MatchIsPointer "yes"
Driver "evdev"
EndSection
You may have to reboot at this point