Even fast websites can seem slow if it takes a while for the content to get to them. This can be partially solved with a Content Delivery Network (CDN). However, most resources usually only shows how to set up static assets and not uploaded content. Learn how to use Amazon CloudFront to cache and serve uploaded content from Active Storage.
Heroku is a Platform as a Service (PaaS), where you can deploy and manage your Ruby on Rails applications. It is one of the easiest platforms to deploy to; allowing you to focus on the development side of things instead of worrying about managing an infrastructure.