which is the best way to add (fire and forget) service to a .net web application

Currently, I am working on a .net web application that is built using html5, sitecore, angular 2.0 and async web api controller etc. All are hosted in the cloud.

Since the database is very slow, downloading a year data to a PDF takes longer time(more than 2 min). So planning to send it as a CSV files to the customer email address. No need to maintain a queue or database, since a maximum of 30 requests comes per day.

What is the best approach to do this? I was thinking to write a separate window service. But maintenance will be there. We will be maintaining a separate application.

Is there a way to add a service to the web application and maintain as a single application like fire and forget?