Follow below steps:
select Help → Settings and Performance → Start Performance Recordingfrom the Tableau toolbar.
Then right click on the source in the Data toolbar and select ‘Refresh’. This will force Tableau to re-run the query.
Once the query completes, select Help → Settings and Performance → Stop Performance Recording from the Tableau toolbar.
This should result in a new Tableau window opening with a workbook called ‘Tableau — PerformanceRecording’
Right-click anywhere in the bar next to ‘Executing Query’ and select ‘View data’
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Below URL gives a very good idea about this