If you would like to troubleshoot a SharePoint Site, Developer Dashboard does the trick for you. To enable the Developer Dashboard you need to create the Usage and the Health Data Collection Service Application. Here is the list of powershell commands to set up the Developer Dashboard.
New-SPUsageApplication -Name "Health and Usage Application" -DatabaseName "HealthDatabase".
$healthdata = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$devdashboard = $healthdata .DeveloperDashboardSettings
$devdashboard .DisplayLevel = "On"
$devdashboard .Update()