Developer Dashboard in SharePoint 2013

Developer Dashboard in SharePoint 2013 improved to provide more information in more accurate way to track and debug issues with page rendering time.

• Running in separate window to avoid affecting rendering of actual page
• Detailed request information per page with chant view
• Dedicated tab for ULS log entries for particular request
• Additional detailed information included for request analyzing
• Works by using dedicated WCF service (diagnosticsdata.svc)
• You can enable (On) it or disable it (Off) by using  Powershell [Ondemand option is deprecated in SharePoint 2013]
• Turn Off by default
• Depends on "Usage and Health Data Collection Service Application" so make sure this service is created [Make sure Its job Timers are running]

Tags in SharePoint Master Page

<SharePoint:DeveloperDashboard runat="server" />
<SharePoint:DeveloperDashboardLauncher
    ID="DeveloperDashboardLauncher"
    ThemeKey="spcommon"
    TouchMode="true"
    TouchModeWidth="30"
    TouchModeHeight="30"
    TouchModePaddingLeft="7"
    TouchModePaddingTop="7"
    TouchModePaddingRight="7"
    TouchModePaddingBottom="7"
    NavigateUrl="#"
    OnClick="ToggleDeveloperDashboard();return false"
    OuterCssClass="ms-dd-button ms-qatbutton"
    runat="server"
    ImageUrl="/_layouts/15/images/spcommon.png"
    AlternateText="<%$Resources:wss,multipages_launchdevdashalt_text%>"
    ToolTip="<%$Resources:wss,multipages_launchdevdashalt_text%>"
    OffsetX="237"
    OffsetY="30"
    HoverOffsetX="219"
    HoverOffsetY="66"
    Height="16"
    Width="16" />

Enable Developer Dashboard
Open SharePoint 2013 Management Shell

$content = ([Microsoft.SharePoint.Administration.SPWebService]::ContentService)
$appsetting =$content.DeveloperDashboardSettings
$appsetting.DisplayLevel = [Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::On
$appsetting.Update() 

Disable Developer Dashboard
Open SharePoint 2013 Management Shell

$content = ([Microsoft.SharePoint.Administration.SPWebService]::ContentService)
$appsetting =$content.DeveloperDashboardSettings
$appsetting.DisplayLevel = [Microsoft.SharePoint.Administration.SPDeveloperDashboardLevel]::Off
$appsetting.Update()