This document discusses high performance functional testing based on Selenium. It begins with an introduction of the speaker and outlines a testing pyramid with unit, integration and functional/UI tests. It then demonstrates how to automate functional tests for web applications using Selenium and discusses techniques for decreasing test execution time, including using Selenium Grid, PhantomJS, HTTP requests instead of Selenium, and parallel test execution. The document emphasizes that faster tests allow for faster development and provides approaches and tools to reduce test bottlenecks and optimize test execution time.