Request Debugging Output tells you about the load times and queries processed when loading a site page. Support may ask for this information in order to determine a problem within your site or page. This feature should not be enabled unless support specifically asks for it. To enable Request Debugging Output, take the following steps:
Go to Debugging & Logging > Debug Output Settings > Check 'Enable Request Debugging Output'
Then, go to debugging IP addresses and enter the IP address of your computer.
Next time you open your site, Request Debugging Output will be displayed at the bottom of the page in a fashion similar to the output of the image below. Send a screen capture or a source view of the timings requested to support.