The two backends, FF and Chrome, have pros and cons.

Firefox: Pros: -Easy to run in headless mode (export MOZ_HEADLESS=1) -Undected by Twitter in headless -Generally easier to grok, follows Selenium API better Cons: -Slower ish maybe -Can't autofocus window

Chrome: Pros: -Twitter optimized -Can autofocus window Cons: -Headless detected by Twitter

Will run benchmarks when I get stable internet.