For those with lower-end computers, the game can load improperly when jumping into a high-populated Haven. At least, on my brother's laptop it does. Textures would be scrambled, character models will be missing their heads and, no matter the distance to the player's camera, there will be a thick line connecting each character's neck to the center of the player's screen. (These lines will end up covering the screen completely in crowded places such as the Arcade, making it nigh-impossible to pick a Gate.) It would be frightening if it weren't so bizarre. As far as I can tell, movement and interaction still work normally when this happens-- you just have to either know exactly where everything is without looking, or stumble around blindly until "Press ATTACK to activate this thing" appears.
These glitches can only be fixed by logging out and back in-- they do not fix themselves when entering another room and allowing the game to load again. Starting in a less-populated area, such as the Bazaar or Town Square, does not set this glitch off.
As the game is set up to automatically aim for a high-populated Haven on login and when returning from the Clockworks, this means it's a very bad idea to... do anything in the game, really.
I'm asking for a setting in the options menu to instead auto-join lower-populated Havens when logging in or returning from the Clockworks, so the game doesn't break itself when attempting to do anything on a weaker computer.
Your issue is a graphics card driver issue, not one of lag. It's been described in some detail in tech support, which is where you should mention this, and include your brother's laptop's GPU, drivers, etc.