Enable/Disable Developer Dashboard in sharepoint 2013

Developer Dashboard is very useful for SharePoint developers and  administrators.It provides diagnostic information that can help to troubleshoot problems with page components that would otherwise be very difficult to isolate.

Developer Dashboard counters measure values for the current request or timer job

• Thread execution time
• Number, duration, call stack information and query text of each SQL Server query generated by the page
• Number, duration, and call stack information of each WCF call
• URL or timer job name
• Current user
• Execution start time
• Any of the preceding statistics for code enclosed by SPMonitoredScope (see Using SPMonitoredScope)
• ULS log — All collected statistics for a specified scope are always logged to the ULS log.
• Developer Dashboard — Performance statistics for a request are available in the browser window.
• I Always prefer to use PowerShell to enable and disable Developer DashBoard

To Enable Developer Dashboard:

$service=[Microsoft.SharePoint.Administration.SPWebService]::ContentService
$addsetting=$service.DeveloperDashboardSettings
$addsetting.DisplayLevel=[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::OnDemand
$addsetting.update()

To Disable Developer Dashboard:

$service=[Microsoft.SharePoint.Administration.SPWebService]::ContentService
$addsetting=$service.DeveloperDashboardSettings
$addsetting.DisplayLevel=[Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::off
$addsetting.update()

Reference:

Developer Dashboard