Hi Binita –
You mentioned that you have huge extracts. The server component “Backgrounder” handles the extract refreshes, and it’s not uncommon to see CPU spikes during this process. Can you provide with some idea of your configuration? Which version of Tableau Server are you running? Are you running a single node or a cluster. How many Backgrounders are configured?
If you have only single background process it can consume up to 100% CPU for larger extracts. You should increase the number of backgrounders processes based on your license. If you have n number of core you can do n/4 for the background process.
I would also suggest refreshing extract during nights or when there is not a lot of user activity.
Here is a good article which gives good information about the Backgrounder process.