2.6.1 added slow SQL queries

Right after upgrading to 2.6.1, I’ve received following slow SQL queries, can anyone advise ‘how do I optimize these queries?’

### 2 Queries
### Total time: 4, Average time: 2
### Taking 2 , 2 seconds to complete
### Rows analyzed 21555 and 21555
SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE XXX=XXX AND
wp_posts.post_type = 'XXX' AND (wp_posts.post_status = 'XXX') ORDER BY
wp_posts.post_date DESC LIMIT XXX, XXX;

SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND
wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish') ORDER BY wp_posts.post_date DESC LIMIT 7, 10;

### 1 Query
### Total time: 2, Average time: 2
### Taking 2 seconds to complete
### Rows analyzed 11791
use dbXXX_wp;
SELECT p.* FROM wp_posts AS p WHERE p.post_date > 'XXX' AND p.post_type = 'XXX' AND p.post_status = 'XXX' ORDER BY p.post_date ASC LIMIT XXX;

use db46425_wp;
SELECT p.* FROM wp_posts AS p WHERE p.post_date > '2007-09-24 16:12:50' AND p.post_type = 'post' AND p.post_status = 'publish' ORDER BY p.post_date ASC LIMIT 1;