I'm in the process of moving creating a runner template using 2023 Q3. I have a representative Windows EXE project I build with ~2500 files included. In testing I found that the build time ~doubled from 13 to 28 minutes compared to 2021 SP1. From the release notes I see the app builder was changed: build times should be shorter on repeat builds.
The trouble is, this relies on the compiled object cache which is always clear when my build jobs start: this discussion illustrates why I do that and it comes down to the fact that I sometimes have different build/test output with and without a clear cache, so in the interest of a repeatable environment I feel that I am forced to always clear the cache.
For testing, I disabled cache clearing and found that the performance improvement is real: the 1st build is 28 minutes but subsequent builds with retained cache are 10 minutes.
So, a few questions for the CI folks:
1. Has anyone else observed significantly slower builds in 2023 Q3+, conditioned on clearing cache first?
2. Is clearing the cache actually needed?
3. Has anyone tried retaining the cache as an artifact so it can be reused to speed up later jobs on different runners?
