we do not share your data with anyone and there are many ways to control the visibility and storage life of your data here.
but the internet is a public space and you should always assume your data could be compromised.
be smart with your password, use tor or a vpn, and use pgp for sensitive communications.
Its not the items that cause the load in problems on some browsers...its the old comments and topics. Ask cleanup borg to remove out dated topics and they can sort it all out :)