The document discusses how a video user profile service originally built in Ruby on Rails was scaled using Elixir. It initially increased resources and used containers, improving performance by 32% and 12% respectively. It was found one endpoint handled 80% of traffic. Rewriting this in Elixir improved performance by 95% and reduced containers by 35%. The results showed Elixir was able to significantly improve scalability and metrics for the growing user profile API.