Perform inventory actions instantly. This is a quality of life improvement plugin aimed to make inventory management is OSRS a little less annoying by predicting what the inventory will look like the next tick.

Or explained by someone who can write:

Normally, most changes in your inventory apply on the next tick (as with most actions in the game). Instant inventory will cause them to render in your inventory giving visual feedback before they actually apply. For example, you drop a fish at the beginning of a tick. Normally it will take about 600 ms for the drop action to process and the item to disappear from your inventory. With instant inventory, it will disappear from your inventory immediately (600 ms sooner), but it won’t actually leave your inventory and hit the floor until the next tick when it normally would.

• by dell_arness2 on Reddit

• Instantly do various inventory actions
  • Drop items
  • Clean herbs
  • Deposit/withdraw items into your bank
  • Equip items
• Configurable visibility of changed and hidden items

See the changelog file