I have 2 slaves and one is working as expected. The other slave is extermely slow while executing the "update" statements. The insert and deletes are fast. I used "check table tbl_name" to see if any MyISAM table was corrupt. Both the slaves are MyISAM only.
I am using (AWS ec2 instance) ext3 for the fast slave and xfs for the the other. Is that the reason why the updates are taking time?