Since my inventory gets more full, has more stuff in it, etc. it freezes, and lags for awhile, then opens up (long on PC, but very bad/long on Xbox).

This still occurs with low gear/empty inventories too, but not very bad like the high gear inventories, frames dropping to 0 for a couple seconds when opening.

Also, when lots of gear is present in inventory, and you're switching between the containers, and it can stutter/freeze up a bit (especially when using Micromanaging button), and selecting something mags for your hands can also freeze the game.