Some kiosks come configured with their GPU drivers disabled. This results in the user interface being exceptionally slow and choppy. Animations will stutter and tear, and overall it looks quite bad.
You can attempt to fix this by simply turning on the GPU drivers in Device Manager, accessible via Redbox Desktop. Techs have noted that this may not work and the device will simply not boot until you enter safe mode, though this doesn't appear to strictly be the case.
One potential route is using a DisplayPort to DVI cable or adapter and re-running the cable through the harness to the door if your VGA cable doesn't work.