Add custom buttons with custom actions in Edit Post screen in WordPress?

Not sure if this is the exact problem you have, but it sounds like the ‘save_post’ hook is going recursive.

What you need to do is unhook, do your updates, then rehook.

{
    remove_action('save_post', array( $this, 'pushfeed_save_post_meta' ));
    // Do update work...
    add_action('save_post', array( $this, 'pushfeed_save_post_meta' ));
}