After a couple days of development and testing between Chrome and capybara-webkit, I tweeted:
very simple Cucumber suite using Selenium; Chrome: 36 seconds, Firefox: 25 seconds. Using capybara-webkit: 7.5 seconds.
capybara-webkit is a headless (meaning it doesn’t have a graphical interface) WebKit driver using the WebKit implementation found in Qt. If you’re not familiar with Qt, it is a cross platform application and UI toolkit. Built by thoughtbot, I suggest you read their quest for full-stack testing here and here if you’re curious how they came to building capybara-webkit.
Installing capybara-webkit on OS X is straightforward. Do give it a try!