Peetz: I think part of the issue is the fact that with just about all of the ingredients, food, etc having no weight - it is easy to collect tens of thousands of items in your inventory without noticing just how much you have. I can understand the game having to take a second to index that large volume.
For me - when the game was first released and the items had weight - I was a lot more careful about how much I was carrying around. Not so much, now.
But yes - I see the slowdown when accessing inventory or stash. Not a game-breaker by any means.
I've never been a fan of inventory management for RPG's (both weight and shape based), so I always ran with a 10,000/infinite weight mod. So yeah I think that's been the problem. I used an increase in stack size mod, and moved a good chunk of my items into stash- now the lag issue isn't so bad (still a pain to disassemble en masse or sell).
BTW, do you know of a mod that disassembles junk all at once, or disassembles grey weapons all at once?