Setting the pixel density will determine the density at which an artboard is exported.
For example, if 2x is selected, an artboard that is 500x500 pixels will be exported and uploaded at twice the size (1000x1000 pixels). Selecting 1x will export and upload the artboard at its original size.
If your prototypes are loading slowly in InVision, you can reduce the file size and increase the loading speed by setting the pixel density to 1x.
To set the default pixel density in Craft:
In the Mac menu bar, click the Craft Manager icon ().
Click the Settings icon (), and then click Preferences.