Optimal map size?

[Zacchaeus]

No, it shouldn't. As Moon Wizard says above it's just on the 4k per side limit and well under budget in terms of size.

[Trenloe]

There are two different things to consider here:
1) Image dimensions. As M_W says above: "Regardless of how much actual space they take up on disk, the whole thing is expanded fully in memory in order to apply all the layers." The image dimensions affect size in FG's memory and amount of time it takes to open the image. The larger the dimensions the more time it will take to open and the more memory it will use. File size on disk has nothing to do with this aspect.
2) File size on disk. This effects the time it takes to share the image with players. The larger the file size, the longer it will take to transfer to each of the connected players. The image dimension itself doesn't effect image sharing time (other than a dimensionally larger image usually results in a larger file size).

[darrenan]

And I'm assuming that closing an Image window in FG does nothing to free up memory? Once the image is loaded, it's loaded, period, right? (I'm talking about the host here, not images shared with players).

[Zacchaeus]

I just tested it and when you open a map memory goes up and when you close it, it goes down again. Opening and closing a module full of maps doesn't affect memory at all.

[darrenan]

excellent, good to know!