If your Mastodon server is being very slow today, it may be due to a DDoS attack on one of the biggest hosting providers.
They are aware of the situation and they're taking action against the attack.
This attack doesn't affect servers running on different hosting providers.
EDIT: Okay, looks like the attack is over, servers seem to be getting back to normal. If you are still having problems ask your server admin, if you are an admin ask your hosting provider.