Can comparing be done faster?

Hi, Currently I am trying to compare 2 excel files.

My first excel file will have this line. I select it by dt1.Select(“Details like ‘(MAZ, 1 vCPU 2GB, 95’”) then get the amount and number of days( 30 days which means a month).

If in first excel file, if it is less than 30 days(not a month). Then I will select the relevant line by dt.Select("[MAZ IaaS Base Compute Services] Like ‘1 vCPU Core , 2 GB’ And [Column1] Like ‘Per Day’"). And times the amount and days to see if the value matches in both excel files.

My question is if all this can be done faster? Something like this below-which is just comparing two columns from different files. But i need to get the relevant row value too.
dt.Select(string.Format(“COLUMNNAME Like ‘{0}’”, row(“COLUMNAME”).toString)).Length >0

As in the above workflow,this is just for one line. I have many more lines e.g. 100 like this. So I would like to ask if there is any other way it can be done faster?

Thank you xoxo