Yeahhhhh, this has less to do with “server maintenance” and more to do with brain-dead design decisions (taverns for everyone! eternal instant respawn at al-Merayah! swarms of confused purge invaders smashing their head against a wall!) coupled with even more abysmal code quality. 1511 is not special here, all active servers have been suffering unplayable performance issues thanks to recent patches from those super-fun Funcom folks
Please follow the stated on the Official servers guidelines to submit a ticket. Make sure to select “Official server performance” as the issue type.: