I am running on a windows environment so I have 5.5 on it , I noticed is writes alot of temp files and at times converts to isam tables ,meaning that my io is going to be high ,from me resource monitor I can see lots of disk activities, it even at times freezes the server for a few seconds, another problem is that the tables have many columns of which the dev uses select * statements, impacting on cache. --------------  As others have mentioned, the best way is to reduce select * from table, especially since your tables are very wide. You are maxing your i/o with data that you eventually never use. There is no temporary solution for that and it hurt bad since your disk is the slowest part. You can increase the sort memory size. That will minimize your database using the disk as a sort staging area. And mysql don't use innodb for sorting so what you are seeing is normal If you were on Linux, you could also reconfigure mysql to use tmpfs for sorting. Essentially dressing up ram as a disk. It help a lot to minimize disk activities  Muriithi