MyISAM InnoDB performance
This is often one of the most mythical subjects of MySQL. To separate fact from fiction, you need to remember the strengths and weaknesses of each Storage Engine. Each Storage Engine and application will govern the workload, read I/O, write I/0, and tuning options.

I have written many posts about how and when to pick one storage engine over the other:


Sep 20, 2011 : Best of MyISAM and InnoDB
May 03, 2012 : Which is faster, InnoDB or MyISAM?
Jul 05, 2012 : InnoDB vs MyISAM with many indexes
Sep 26, 2012 : Choosing MyISAM over InnoDB for these project requirements; and long term options


I have many more posts but you can start with these.