Slack chose webpack as their build tool, but it wasn’t fast enough.

Our build took minutes, not seconds: a far cry from the sub-second concatenation we were used to. Slack’s web teams deploy up to 100 times on any given work day, so we felt this increase acutely.

Let’s just say they went to work and came up with several techniques to speed up the build process.

webpack is a fantastic, versatile, tool that does not need to cost the earth. These techniques have helped us reduce our median build time from 170 to 17 seconds and, while they have done much to improve the deployment experience for our engineers, they are by no means a complete work.