My Scottish girlfriend, from North Ayrshire, uses 'Creeping Jesus' to describe my elderly mother with Alzheimers, who wanders around the house silently, and listens to conversations from the other side of doors. Therefore an alternate meaning is, 'Always close by and making no sudden movements'?
Reading the 'Origins of the Term' paragraph of the Wikipedia entry, key bits are 'in sight of everyone' and 'moving quietly'.
This description emphasizes the slowness.
Creeping to the cross