How exactly does "Save Contents to Image" work?

Hi!

The question is: if I make a 2GB image for one or more browser caches and choose "Save Contents to Image", will the program update the whole 2GB image by writing new 2GB over the old 2GB, or will it rewrite only the files within the image updated since the last session?

I thought about using SoftPerfect RAM Disk for browser cache. Not for speed performance, but partially for saving HDD/SSD from rewritable information from browser profiles that is rewritten at least every minute.

So is there any sense in using a 2GB image for Firefox and Chrome profiles? Or will those 2GB in the end write more data after the secession than without RAM disk with "Save Contents to Image" option?

The image file is written in 2 MB blocks, and only the blocks that have changed since the last read or write will be updated.

In other words, when saving data to an image, only changes are written, not the entire image.

P.S. The "Save Contents to Image" option was renamed into "Save to File on Shutdown" in the newer versions, to make its function clearer for new users.