How can I reduce the size of the MASTERS folder inside Photos?

I was trying to find out why my Photos app database is SO large. I have 8 gig of jpg photos.

I chose to NOT copy them when I imported them into Photos.

Yet my Photos app database is 8g as well! That's a lot of space to use when I didn't even copy the JPG into it.

So I went hunting to learn what was going on.

You can go to your Pictures Folder and find the Photos Library there. Right (or Control-) Click on the icon and select 'Show Package Contents'. A finder window will open with the Library exposed.

Here is what I found:

• The "Masters" folder is very small. 300MB.
• The "Previews" folder is a similar size.
• "Thumbnails" are under 1G.
• It's the "Resources" folder that is many gigs in size.

Very interesting. So in a sense, it could be even worse!

• That is, apparently the setting prevented the "Masters" folder from getting 8 gig of photos copied into it.
• But even so, "Resources" ended up with 6.5G in it -- even though no files were copied!
• Wild.
• Other photo management apps (e.g., Lightroom) have sort of a 10% overhead, not a 90% overhead -- i.e., close to the same size as the actual photos themselves.

I should probably start a fresh question, now that you have solved half the mystery: Yes, the actual photos were not imported into Masters, but Resources gets really big!

So here is my question: What the heck is going on with RESOURCES? How can I make that folder smaller? I mean, at this point, if I were to choose to import all my photos, it looks like that would double the size of my Photos installation. Of course, I'm not going to do that. Because, already, I don't have enough space for everything on my hard drive. And Photos, even when not importing, takes up a lot of space.

I need to get this folder under control. How can I?