@melix Been there!
I recently revamped the #cipipeline of a service at work & managed to cut down the time by ~60%.
The trick was to avoid #docker (dind) & reuse the already provisioned resources (ie the build container) while ensuring a #ReproducibleBuild: while docker was used for almost anything, turned out the only time we really needed docker was for consumer #ContractTesting & #EndtoEndTesting and w/ a bit of effort we could safely run most of the tests in the original container.