The purpose of the profiler is for aiding in diagnosing slow page load times. This should never be left enabled on a deployed website. There are actually two aspects of disabling it:
1. Turning off profiling under System (menu) -> Configuration (menu item) -> Developer (tab on left) -> Debug (accordion section)
2. Make sure all calls to Varien_Profiler::enable(); are commented out in your index.php file.
The first one I mentioned here only serves to disable the output of the profiler results to the end of the page after everything else has finished being processed. While this will fix the issue with the display, it doesn’t actually turn off the profiler at the fundamental level, so your server will still be wasting the server resources by timing and keeping track of how long lots of different portions of Magento take to execute. This comes in handy in circumstances when you want to print the profiles to a log file on a struggling production site for debugging reasons while still being transparent to the sites customers. So basically what I’m saying is make sure you have it turned off in the Magento admin and make sure that the calls to Varien_Profiler::enable(); are not being called in the index.php file or you’ll see a performance penalty on the site, however slight/large it may be.