Best way to efficiently process millions of forms? [closed]

I am building an application to parse forms and call an api endpoint to process those forms depending on the information they hold. The endpoint will return a single data point for each form which will be returned to the client. The whole process is time sensitive, so I want it to be as fast as possible. My only solution so far is to have multiple instances of the api along with a load balancer. Are there any other designs I can look into?