Exported" layers to files" don't match original filesizes

[JerryandLoisPhotography]

Hello,

I need to better understand exporting layers to files.

Suppose I have source folder that has 4 TIFFs, no channels, no additional layers, none that are smart objects, etc. Boringly simple.
base.tif
xxx.tif
yyy.tif
zzz.tif

I create a stacked file with base as the bottom layer, and xxx, yyy, and zzz as the additional three layers.

Now I opt to export layers to files to a separate destination folder. No compression.

At the end I have 4 new files.

The filesizes are different (please see attached JPG), visually, the source and dest files seem to be the identical. In particular with my simple test:

Can I reliably expect that the destination files are the exact same as their sources, visually (not just by eye)?

Why would the destination files be a different size? I'm hoping the answer has to do with metadata, not the image data.
While the files I mentioned are simplified for testing purposes, I have real-world files whose sizes grow by 30% when I stack and then export them back out.

Thanks!!!

[c.pfaffenbichler]

In the screenshot it seems the exported images are smaller, not larger, in file-size than the originals, so please provide a meaningful set of images. 

[JerryandLoisPhotography]

As I said, the first case was with simplified files, to prove that output sizes don't match input sizes.

For a real world example,  please see this dropbox link:
https://www.dropbox.com/sh/i2pn42wsawmyr1q/AAB3o3xUMTw8HXYu-NNtd2Bna?dl=0

AND - note the attached screen shot.  Highlighted file originals are each about 66mb, exported are 201mb.  Over 300% increased filesize.

There's another issue - the source files, once modified, take a very very very long time for each to save, regardless of what kind of change was made.  The versions that were exported from a stack save in a short, reasonable amount of time.  I don't know why...

Hoping for some insights...

[c.pfaffenbichler]

It seems the originals are zip-compressed, the resulting files aren’t. 

[JerryandLoisPhotography]

This is quite shocking to me.  At no point that I can consciously remember did I opt to ZIP these.  That's something I've never included in my workflow ever, over the last zillion years.

This also explains the insanely long save-time required...  <shaking my damned head 'til it hurts>

Good to learn something here, even after 20+ years w/PS.  Question:  Besides using either "save as" or "save a copy", is there a way to force the file to unzip itself when hitting the save button?

I have an entire folder of 140 files that I've been working on, each taking 3 minutes to save, which was just driving me cwazy and eating up so much of my time!!!  I need to get these all unzipped so I can continue working.

Hoping there's a script or action (if the latter, probably using save-as) to get this systematic mistake corrected ASAP.

Thank you for catching this <shaking my head again!>
Jerry

[c.pfaffenbichler]

Question:  Besides using either "save as" or "save a copy", is there a way to force the file to unzip itself when hitting the save button?

Not that I know of; I guess you could use File > Scripts > Image Processor to create copies without compression and replace the originals with those. 

[JerryandLoisPhotography]

Right - that's a tool I'd forgotten about.  Still blown away and glad for the explanation of the unbearable slow save times.

Back to my original question:  filesizes of original vs. exported layer do not match.  Any insights on why this is, and is there any change to the actual image content (guessing this is a metadata related behavior)?

Thanks!

[c.pfaffenbichler]

If I resave »0141-23-Fireworks-Bellevue-Jerry-and-Lois-Photography-TPAI.tif« without compression it seems to be 205,9MB, just like »OUTPUT-_0003_0141-23-Fireworks-Bellevue-Jerry-and-Lois-Photography-TPAI.tif.tif«.