I've got a WP blog running on my dedicated box, a 2.4Ghz Xenon Linux box with php and MySQL. The site currently has ~8,500 posts and I'm adding about 50-70 a day. The site is currently only getting ~1,500 unique visitors a day.
As I've added more posts, I've noticed a large increase in server load. It used to hover at 0.6 (15min load), now it's rare that it'll drop below 2.5 (15min load). I took a few actions to try and speed the site up, but nothing seemed to do the job;
1) Increased MySQL cache size
2) Installed wp-super-cache (i only use the standard cache feature)
3) Debugged all my plugins, and managed to lower the number of SQL queries per page from ~60 to ~30
When I setup the site, I googled for large wordpress sites, and found some that had in excess of 50,000 posts. Making me believe WP would be the way to go. I still think it is, but i can't figure out why my load is so high.
Does anyone have experience with a site of this size? Or has anyone experienced similar issues?