I'm assuming that putting an item in a chest is much better than dropping it on the ground? I say this because if it's on the ground, the game has to remember it's exact position in 3D space, as opposed to just being "in" the chest? Seems like the game could remember many, many items being stored in a chest for every one item on the groudn that it has to remember "steel mace, coordinates = 99082, 81712, 83514," for example.
Yes, for the reasons you mention. Additionally, when you are in range of objects that are thrown on the ground, the game also has to load the geometry and textures associated with that object, and also perform processing on that object because it is active within the 'world' and not just a set of numbers in a container (which is what happens when it is stored in a chest, which is only processed when you look inside it). The loading of geometry/textures of active objects will increase the amount of RAM used at any one time. Also, memory fragmentation also increases because of the increased frequency of stuff being loaded in and out. You will also notice that when the game starts running out of memory (because there is too much stuff around), it lowers the detail on objects to free up space.
Edit:
Note that the size of your savefile is not the only consideration. It is also down to how much stuff is in the local area that the game has to render. For example, if you are in an empty room and your savefile is 20Mb, then there will be a lot of RAM available to load the savegame in, and so no problems will arise. However, if you now drop lots of stuff so the game has to load all the geometry/textures for all the dropped objects, then there is less RAM available and so a 20Mb savefile could start to cause problems because all the free RAM is taken up with all the extra stuff the game has to render. This is why some people with large save files have no problems, while other players do. It is down to the amount of free RAM at that point in time.
Edit: You be aware of this one, but I will add it for clarity.
The game stores lists of 'differences' that you make with the world. For example, if you have a table full of cutlery and food, and you don't interact with it, then when you leave the area, no extra data will be stored. However, if you jump on the table and kick all the cutlery and food everywhere, all those objects will now be in a different place, all of which has to be stored (thus, savegame bloat).
Does having multiple copies of an item in a chest increase the save file much (if at all?) For example, if I put an iron ingot in a barrel, the game has to basically remember "Iron Ingot, 2nd Barrel, Proudspire Basemant, Count = 001"... but if I put 499 more, it's just changing the number it uses to keep track of how many, right? A "count = 500" doesn't take any more space to store than a "count = 001", right? I guess the question I'm asking is, am I hurting myself by storing tons of each alchemical ingredient, or is it all the same once I've got one of each... each additional item of the same type doesn't add any size?
Theoretically it shouldn't, assuming the game is written in such a way that opimizations like this are considered. The game is likely to store the object type, and have a counter for the number of copies of that object that exist. Thus, increasing the number of a particular object is only going to increase the counter number. No extra data is likely to be stored.
Building on the second question, though, it would seem that for items you wish to keep, it would be better to keep all identical items in a single container? Is this correct?
It may help fractionally, but you will end up doing a lot of work for very little gain. The amount of memory that objects take up (when in a container) is likely to be very small. As long as they are stuffed in a container, you will get the most benefit from doing that. The largest memory footprint will be from the geometry and the textures for that object, which wont be loaded up as long as they are in a container somewhere.
For lower-level enemies, are bound bows the way to go to avoid arrow cluttering throughout the landscape? Or does the game remember those arrows for quite awhile too (you can definitely see them laying on the ground after a fight). Do arrows ever clean up?
Not to my knowledge. I fired a bound arrow into the floor just outside my home in Whiterun ages ago, and it is still there. I assume these are never cleaned up. However, patch 1.4 does mention a fix for ...
- Fixed issue with dangling scripts not properly clearing from memory
Not sure what this relates to. Maybe it is for arrows?
Does the 30-day "clean up" only count days that you don't visit an area? For example, if I want to cleanup Whiterun, should I avoid visiting it for at least 30 days... I don't want the timer to "reset" every time I go back.
Not sure about that one. I would hope it doesn't reset because it could cause a lot of problems, one of them being what you just mentioned.
Another thing that will reduce the size of your savefile,
is to reduce the number of active quests that you have. Each new quest activated will increase the size of your savefile, so completing them will help keep the savefile size down.