Ok, on the search page your slowdown is definitely coming from mysql. Averaging well over 20 seconds to do the queries necessary for the recent posts. I see that you're returning 50 results on this. You might try running this down quite a bit to around 10-20 to see if that helps for that specific page. The search pages definitely hit the mysql server the hardest out of all of them.
The last one, very little of the time was taken by mysql, 0.147, but it still took close to 3 seconds to generate the page and deliver it which is still fairly slow.
Any idea on your server specs? Memory, CPU, etc.
Try the same thing on a few other of the pages like, the main forum listing, the postlist and a couple of topics to see what type of results you get.
