ibf_sessions causes frequent CPU overloads

[globex]

My website keeps getting CPU exceeded messages. Tracking the logs I've narrowed it down to one of my IPB forums. I've recently updated this from to the latest 2.3.x version from 1.2.x because it was getting ibf_sessions problems before too.

Here are a few SQL error messages I get:

# Wed Jul 23 14:58:19 2008

# Query_time: 2  Lock_time: 0  Rows_sent: 0  Rows_examined: 0

use my_forum;

INSERT INTO ibf_sessions (id,member_name,member_id,member_group,login_type,running_time,ip_address,bro

wser,location,in_error,location_1_type,location_1_id,location_2_type,location_2_i

d,location_3_type,location_3_id) VALUES('dee207e637888b0a4490e570667b9c04','',0,2,0,1216846697,'89.248.169.90','Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)','Members,0,',0,'',0,'',0,'',0)

# Wed Jul 23 15:13:55 2008

# Query_time: 2  Lock_time: 0  Rows_sent: 0  Rows_examined: 0

use my_forum;

DELETE FROM ibf_sessions WHERE ip_address='74.6.22.164'

# Wed Jul 23 17:30:16 2008

# Query_time: 2  Lock_time: 0  Rows_sent: 0  Rows_examined: 0

use my_forum;

INSERT INTO ibf_sessions (id,member_name,member_id,member_group,login_type,running_time,ip_address,bro

wser,location,in_error,location_1_type,location_1_id,location_2_type,location_2_i

d,location_3_type,location_3_id) VALUES('f1b63747dad0ae86fe7a8c802b9406e0','',0,2,0,1216855814,'200.109.132.154','Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.1)',',0,',0,'',0,'',0,'',0)

What can I do to help prevent these issues?

[Aether)]

Change the table engine to memory.