Everything you execute in a view affects response times. In many situations, you might want to return a response to the user as quickly as possible and let the server execute some process asynchronously. This is especially relevant for time-consuming processes or processes subject to failure, which might need a retry policy. For example, a video sharing platform allows users to upload videos but requires a long time to transcode uploaded videos. The site might return a response to users to inform them that the transcoding will start soon, and start transcoding the video asynchronously. Another example is sending emails to users. If your site sends email notifications from a view, the SMTP connection might fail or slow down the response. Launching asynchronous tasks is essential to avoid blocking the code execution.

Celery is a distributed task queue that can process vast amounts of messages. It does real-time processing but also supports task scheduling. Using Celery, not only can you create asynchronous tasks easily and let them be executed by workers as soon as possible, but you can also schedule them to run at a specific time.

You can find the Celery documentation at http://docs.celeryproject.org/en/latest/index.html.