Run into Two Issues

3d Game Models. Because of the number of textures files that some 3d models use, some of these models each are taking up 30-90 megs of space, most of it just to store all the texture files. Already my main city map is over half a gigabyte in size. What is the best compression for these textures?

2). Save Games, because Unreal uses set Nodes to link everything up for saving slot game variables, save games are gonna be a problem when the number of variables I have to save is going to be over 2,000. I can’t use the slot save system. Can the save be done instead with a data table file or data struct?

For your save game issue, you can store structs in your save game. So create a custom struct in the content browser, add whatever variables you need, and then add that struct to your save game. Then you can set the struct rather than setting 100s of variables individually.

Your map file is probably large because of the lightmaps, 500mb is reasonable for that really, in a large map. But on the textures, probably you will need to look at your workflow. Not every model needs a unique texture, you could use material instances with brick textures, wood textures, etc. or whatever you need that re-use the same textures. You can also pack your textures into one so that multiple meshes share the same texture.
Texture masks can also help if you find yourself relying on multiple material slots Using Texture Masks | Unreal Engine Documentation
The content creation sub-forum might be a better place to get a more detailed answer on that though.

I’m not sure how to set that up just yet with the save option. But sounds just like what I need. My map only has just 1 lightmass volume in it for the Lighting and the lighting comes from the Sky Sphere BP. I haven’t installed in
the lights yet. The map has a mini city, surrounded by 3 regions of wilderness. It’s About 2 km so far in size. Takes about half an hour to walk from one end to the other.

The issue I’m having now is the frame rate of my map is jerking along when walking around the map. Still can move around ok but it feels a bit sluggish, but it could be because of the Landscape because I used the default building landscape tools, and maybe if I export the landscape out into a 3d mesh then reimport back in it that might resolve the sluggish draw update, because the editor is trying to update all of the triangles that make up the Landscape when i walk around and its slowing the frame rate and rendering down. I suspect this is only an issue when building
the landscape from inside of the editor. I also have the Texture Resolutions settings on minimum.