Some people say when they're running on battery their external usb-attached mouse has a sleep pause every 5 seconds or so. I experienced it myself.

This problem appears when you install 'laptop-mode-tools' to save energy and cool down the system by giving sleep orders to unnecessary operations. But usb-mouse shouldn't sleep at all. that's why we need to alter a file:

      sudo gedit /etc/laptop-mode/conf.d/usb-autosuspend.conf

change the following line: 

      AUTOSUSPEND_USBTYPE_BLACKLIST=""

with:

       AUTOSUSPEND_USBTYPE_BLACKLIST="usbhid usb-storage"

save and close. comming back to terminal. save all your work because you are going to restart your system.

       sudo reboot