Pace
This is the small red (by default) animated bar shown at the very bottom of each page to indicate the page is loading. It will disappear once loaded.
Changing colors
Options Panel → Design → Colors → Global colors → Other → Page progress barPick any color you like.
Switch on or off
Go here to Hide the Progress bar:Options Panel → Components → More → Pace progress bar → Enable Pace progress bar?
Go here to disable the Pace code:Options Panel → Advanced → Performance → Disable JavaScript output → Pace Page Progress