All items that you never looked at in your inventory should be marked in someway, for example being in a colored text.

This way I can easily see which of the hundred letters/ingredients/books I've never read/eat before without stopping on every item I'm not sure is old.

why not just note what youve picked up ?

Sure I could. Should I write "New item added"?

pretty much every other game has this function.

That would be a good idea. I do like trying to read the books in the game but can never remember which I have read by title.

Consequence: More save game space. This game already suffers from bloat. Every extra feature at this point would only make that problem worse.

I didn't think few world co-ordinates and object data would be so cumbersome. Skyrim saves have proven me wrong though. Skyrim is no way a lot bigger than FO3 or FONV, yet the saves seem much bigger. Is it the new engine?

It's a good idea. i like the idea of the item being highlighted or a different color until you examine it. How much save space could that take??

I don't think this would emcumber the performance in any noticeable way. It will only be highlighted until you looked at it.

Most people wouldn't think that a few ash piles, a few glowing nirnroots and a few arrows on the ground would take that much space either... but it's already causing problems.

You are talking about physical objects.