Assuming that you have a huge Excel spreadsheet which contains 1000 or more rows and columns. The 'Read from Excel Worksheet' Action should take some time to read all the contents. Moreover, in order to search for a specific value inside the %ExcelData% datatable by looping though each column and row of the aforementioned variable should take some time and reduce your Process's performance.
Hence, the most convenient way to deal with huge Excel files is to treat them as databases and execute SQL queries on them. For additional information on how to use SQL on Excel files, refer to this article.
In the Test.xlsx sample document of the aforementioned article, the 'SELECT * FROM [Students$]' query will read the worksheet's contents much faster that the 'Read from Excel Worksheet' Action.
Furthermore, suppose we want to have the Student ID of a specific student. Instead of looping through all the students in order to find the desired one, we could execute the following statement:
SELECT[Student ID]FROM [Students$]
WHERE [Full Name] = 'Steve B'
The above query will be executed much faster than using a loop.