Yes, the processing time of India Evisa will be postponed on national holidays because the Consular Department of the India Ministry of Foreign Affairs will be closed at this time.
List India Holidays and Observances below:
Along with technology development, traveling to a distant country nowadays does not take months or weeks on streets but just a few hours with visa process shortened into a few minutes. If you are a US. citizen, here are some useful information about Indian eVisa for you.