Raw performance, in the sense of single core performance, is still one of the most important factors for us. Yes, we have parallelised tests, in different modules, etc. But there are still many single threaded operations in the build server. Also, especially in the cloud, IO is a bottleneck you can almost only get around by provisioning a bigger CPU.

Our CI run smaller PR checks during the day when devs make changes. In the “downtime” we run longer/more complex tests such as resilience and performance tests. So typically a machine is utilised 20-22/7.