Mysql Io 读取数据数值上百亿高，求解

网站三天两头的变慢，找了很多原因,但是问题没能解决。网站变慢的时候，服务器变得很卡.

[show processlis] 命令会打印出
+----------+------+-----------------+------+---------+------+--------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----------+------+-----------------+------+---------+------+--------------------+------------------+
| 19021447 | root | 127.0.0.1:28253 | o2o | Query | 17 | removing tmp table | DESC fanwe_youhui_log |
| 19025616 | root | 127.0.0.1:32578 | NULL | Query | 0 | NULL | show processlist |
+----------+------+-----------------+------+---------+------+--------------------+------------------+

分析慢查询日志 N多下面的数据：
# Time: 140621 14:10:15
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 24.078125 Lock_time: 0.000000 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331015;
DESC fanwe_youhui_log;
# Time: 140621 14:11:51
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 14.312500 Lock_time: 0.015625 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331111;
DESC fanwe_youhui_log;
# Time: 140621 14:12:06
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 10.843750 Lock_time: 0.015625 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331126;
DESC fanwe_youhui_log;
# Time: 140621 14:13:14
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 26.656250 Lock_time: 0.000000 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331194;
DESC fanwe_youhui_log;
# Time: 140621 14:14:32
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 10.312500 Lock_time: 0.000000 Rows_sent: 1 Rows_examined: 0
SET timestamp=1403331272;
select group_concat(focused_user_id) from fanwe_user_focus where focus_user_id = 33073 order by rand() limit 50;
# Time: 140621 14:15:10
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 21.359375 Lock_time: 1.953125 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331310;
DESC fanwe_youhui_log;
# Time: 140621 14:16:28
# User@Host: root[root] @ [127.0.0.1]
# Query_time: 16.984375 Lock_time: 0.000000 Rows_sent: 11 Rows_examined: 11
SET timestamp=1403331388;
DESC fanwe_youhui_log;
===========================================
按道理说 DESC Table 命令应该是很快的命令，今天发现 Mylsq IO数据特别高，对这块我也不了解，想请大家分析下：

我打开任务管理器，然后查看进程，在I /O 读取这一列数值是 43,658,476,259 I/O 写入数值是：75,652，817