I agree, there should be an "Open registration day", make it a pattern. Exactly every 7 days could have open registration to minimize chances of people thinking the registration is shut down completely forever(Time zones are probably what's keeping users from finding the registration open, people wanting to register have to either wait days/weeks or stay up way past their bedtime/stay home from school). But, it may have lag every week, but just include a warning in a topic(Or put the warning on the homepage) that the game will lag on those days the registration is open.
OR, have the registration open all the time, and have a set day when the server updates to complete the registration of all users that have registered before that time. It will still lag a bit on those times, but put an automated warning in chat if possible. If warnings in the chat aren't possible, then put a message on the site's homepage saying something along the lines of "There is a time the game will encounter lag which is perfectly normal"
As for General Chat, and I know this needs the source code, but there should be a limit to the amount of posts that can be made every 5-10 seconds in General Chat(Wait 5-10 seconds before posting again in General Chat). Local should have a shorter limit as people can just block or lead others away from Local spammers(Or tell people how to turn off Local chat, teaching is another good use of time). The instructions of how to turn off chats could be put on the main homepage for everyone to see(So people will not have to visit the forum to learn how to turn off ingame chats).