As reported on Kotaku Japan, PlayStation Vita games actually load faster on cartridge than they do when digitally downloaded.
When you play games via UMD using the original PSP, games load way faster when you download them directly onto a memory stick. It appears as if the opposite thing happens with the PS Vita.
Kotaku Japan uploaded a video to prove this. The cartridge version of Uncharted: Golden Abyss loaded four seconds faster than the downloaded version.
Check out the video below: