I just got the game and installed it (that's a whole different annoyance).
After having the game freeze during a load, I ran the following test:
1) Created a new scenario, Settler, Huge, 1 opponent, 0 city-states. I also set that the random number seed changes. Saved it, exited the game.
2) Copied Test01 to Test02 and Test03.
3) Started the game, loaded Test01, ran my warrior in a straight line until I found a Ruins. Entered the Ruins, noted what I got, saved, exited the game.
4) Started the game, loaded Test02, ran my warrior in a straight line to the same ruins. It wasn't exactly on my line, so when I moved off, I went through the same hexes as previous. I DID NOT enter the Ruins.
5) Saved the scenario, entered the Ruins. Didn't get what I got the first time. Reloaded the scenario, tried again. Repeated this about 10 times until I got the same thing. Note that I DID NOT exit the game, merely used ^L to reload after each failure.
6) Saved the scenario, exited the game.
Examination of Test01 versus Test02 was interesting. Test01 was about 450 KB. Test02 was 3.7 MB.
Preliminary thought is that it's saving some sort of memory leak, and it adds to the leak EVERY time you reload a scenario. So if you find a Ruins, save, then hit it multiple times, reloading until you get a result you like, and you do this several times, well, that file's gonna get LARGE.
I saved Test03 for another run (which I haven't done yet). Go to the Ruins, save, enter the Ruins. If I don't get what I want, exit the GAME, restart, reload, try again until I get the same thing, then save the scenario. The objective will be to see how big the file gets on the final save if it's always from a fresh load of the game and scenario.