[Tanasinn]

When using certain items from your item belt, you are hit with varying degrees of lag. The items that I know of are all food, all forms of bear trap, and plant seeds for farming.

From what I can tell, the items are rendering your entire inventory every time you try to use them. To show this, if you fill your craft inventory with things and have your inventory tabbed to 'Craft', you will have a lot of lag on using the item. If you then tab to an empty 'Other' tab, you won't have (as much) lag. I don't know if this is fixable, but it seems unintentional as other items don't have this problem(Buckets, shovels, fishing rods, etc.).