The fact that you're getting lag from that is pretty strange indeed. Have you tried using the "CharacterUsedItem" events directly in Osiris? Did those lag as well?

Code
CharacterUsedItem((CHARACTERGUID)_Character, (ITEMGUID)_Item)
CharacterUsedItemTemplate((CHARACTERGUID)_Character, (STRING)_Template, (ITEMGUID)_Item)

LaughingLeader's DOS2 Mods