It's because of the "Object Teleporter" feature I added in the last update. Since it hooks onto the game's packet receive function, it would slow down somewhat due to the time it takes to send the coordinates to the cheats window.
Edit:
In the new update (V0.1.1), I have added the option to enable/disable this feature so that you can only use it when you need to (e.g. during silverwastes chests)