WordPress 2.7 beta 3 extremely slow backend

hi,
i have just upgraded all my wordpress sites from 2.6.3 to 2.7 beta 3. what i wish to highlight is the extremely slow editing and posting that resulted to errors.

here are some troubleshooting that i have done and the results;
1. disabling all the plugins and widgets. result: still slow.
2. turbo charging it with gears. result: still slow though reduced around 5-10 sec.
3. delete unused and disabled plugins. result: just like no.1
4. take so long to post or edit, tried few lines of words instead of long post. result: backend was put into halt, freezes and error message appear such as;

WordPress database error: [MySQL server has gone away]
SELECT * FROM wp_postmeta WHERE post_id=1066 AND meta_key=’forumlink’;

upon refreshing frontend/frontpage. post sometimes missing. A ‘Nothing found 404’ page is generated.

thats all for now. i think i need to downgrade it back to 2.6.3
cheers.