Hi guys, I have this blog with that amount of data running on a dedicated server. It was the merge of about one hudred of blogs, this is the reason of those high numbers, tags especially.
Among the plugins I have WP Super Cache, and I think it's doing its job fine.
While monitoring MySQL slow queries and system memory, I find that under certain circumstances the consumed ram grows until it fills all the available memory, at this point what happens is epic, "Error estabilishing an error connection" from the frontend and backend, queries that took 100+ seconds to complete and reboot is needed.
An example of a slow query is:
# Query_time: 194 Lock_time: 0 Rows_sent: 1 Rows_examined: 50238 SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) WHERE 1=1 AND ( wp_term_relationships.term_taxonomy_id IN (7,24,25,26,27,28,29,30,31,32,33,34,35,36,37) ) AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish') GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 1;
Now I'm going to upgrade the system with 4GB more of ram, I hope 8GB will be enough, but what it concerns me is if teorethically WordPress can handle so many posts and tags.