When there is a large number of objects on the screen with pixel offsets moving around, mouse commands and any other things having to do with the interface become progressively unresponsive. This is single-user mode only, however in some cases over time mouse commands in hosted worlds also begin to become unresponsive. Regardless of how slow the mouse commands/interface becomes, the keyboard commands consistently run at full speed.

The same issue used to happen with keyboard commands/verbs when a game used a lot of pixel movement, but that was fixed.