The enter_bug.cgi page ("new" on the toolbar) takes 12.8 seconds to finish loading. Usernames and passwords that are autofilled will not be filled until the page has finished loading.
Why is this a problem? Because it seems to be doing nothing. The page just sits their, not finishing loading. After the long wait, and only when the page has finally actually finished loading, only THEN does firefox fill in the username and password.
Page size for show_bug for a Fedora bug is about 2.2MB, including 37,000 <option> tags. It looks like there's seven copies of the component list in there. Something is.. weird.
This should be fixed now. Thanks.