Photoshop size become huge (Artboards)

[bryanw37228651]

Why my file become very big when im working with artboards ?

1920x7211 px 

all layers is smart object and my file became bigger than 2GB(which 5GB in psb) 

[Sunny6]

Hit CTRL + ALT + I and scale up by a percentage of 1.15942028985507. This should leave you with all artboards at the right size...