Why does test suite performance matter? First of all, testing is a part of a developer's feedback loop (see @searls talk) and, secondly, it is a part of a deployment cycle.

It is hard to appreciate how important really fast (and reliable) hot reload can be during development, unless you have experienced it yourself. Developers report that it changes the way they create their apps, describing it as being like painting their app to life.

I like bundlers. Correction, I like fast bundlers. Bundlers that help me tighten the feedback loop and help me focus on the code. Not bundlers that make me doze off, waiting for the recompilation to finish, while my CPU fan sounds like an old hair dryer.

We do the smallest thing possible and get it out as quickly as possible.

We check in our code at the entry point of a pipeline, version control (Git and Github in our case), and then it’s taken through a series of steps aimed at assuring quality and lowering risk of releases. Automation helps us keep these steps out of our way while maintaining control through fast feedback loops (context-switching is our enemy). If any step of the pipeline breaks (or fails) we want to be alerted in our communication channel of choice (in our case Slack), and it needs to happen as quickly as possible while we’re in the right context.