You can also use the
SharePoint Developer dashboard to troubleshoot problems with page components. If your Developer Dashboard doesn’t offer you enough information, you can make use of
SPMonitoredScope in your code.
How to enable it ?
To enable dashboard you need to create the Usage and Health Data Collection Service Application.
Use the below powershell command to create the service application.
New-SPUsageApplication -Name "Health and Usage Application" -DatabaseName "SP2013_Health_and_Logging_Database".
Once you run the above command it will create the service application with the name Health and Usage Application and the respective database.
Once you have created the service application you have to enable the dashboard.
In the previous versions we use to get three options ON/OFF/OnDemand settings for the dashboard.
Now in this version you will get only two options ON/OFF.
To enable the dashboard, we will use ON setting and use the below powershell command.
$svc = [Microsoft.SharePoint.Administration.SPWebService]::ContentService
$dds = $svc.DeveloperDashboardSettings
$dds.DisplayLevel = "On"
After executing the above powershell command open your site on top right hand side of your site, you can see an icon to launch Developer Dashboard.
Please refer this link for more information.