The engine needs a big overhaul. With the recent Polaris update, it has gotten broken. The ice physics make wizards go too fast for the server, as it will appear that the wizard is teleporting. If someone fishes while on ice, they will appear to continually fly to anyone else besides that wizard. The server can only handle normal walking. When holding the right mouse button and using it to spin rapidly, the server won't show that wizard spinning rapidly.
There is a glitch that can allow you to pass through very thin walls. This is how wizards got on to Elik's Edge in the Shopping District, the water gate in Olde Town and the space behind the door in the Life Tower.
Walruskberg seems to load an extra amount of time compared to other areas in the game.
