That's not a question anyone can answer for you, Manoj. There are far too many variables: server or desktop? Excel or SQL Server? Network conditions? Type of disk (SSD vs. physical)? Physical or VM? Tableau Server (assuming it's that) architecture? And how will Tableau ITSELF change over the next 5 years?
What are you trying to achieve with that question? What's the underlying problem you're trying to identify?
Product: Tableau Server
Performance Issue Based on time taken to retrieve the reports in the longer run
Product Version: Tableau Server 10.5.11
OS: Windows Server 2012
Datasource: MS SQL SERVER