Time-outs while loading page edit screen on support site

[schlessera]

When I try to edit a page on the support site (like ​https://wordpress.org/support/wp-admin/post.php?post=8&action=edit), I get time-outs.

On Google Chrome, I get a time-out after 1 minute, and Chrome shows me a net::SPDY_PROTOCOL_ERROR.

On Firefox, I get a partial page. The interesting thing is that the partial page in Firefox seems to always end in the same spot, on a sub-menu item in the admin bar under the + New button (see attached screenshot).

I suspect that this might be a bug or performance bottleneck that can be traced back to this admin bar rendering. Probably something like a menu item that contains a BuddyPress count or similar.

[schlessera]

Screenshot of where the page rendering stops in Firefox

[ocean90]

In 6564:

Support Forums: Disable post meta key lookup for the Custom Fields meta box.

Prevents a performance issue when trying to edit posts.

See ​#WP33885.
Fixes #3436.