Note about GitHub Windows Actions runners: I think I understand what is wrong with them, though it's somewhat conjecture since I don't actually know how it works internally.
It looks like the free CI runners have C: drive pointing to a disk that is restored from a snapshot, but often times it hasn't finished restoring the entire snapshot by the time your workflow runs, so IO can be very slow, even if you don't need to read from the still-frozen parts of the disk. Some software ran inside workflows will do heavy R/W on C: drive, but it's better to move anything that will be written to disk, e.g. caches, to D: if possible. This often leads to much better performance with I/O and more predictable runtimes, particularly when there isn't a lot of actual compute to do.
alt Hacker News
Note about GitHub Windows Actions runners: I think I understand what is wrong with them, though it's somewhat conjecture since I don't actually know how it works internally.
It looks like the free CI runners have C: drive pointing to a disk that is restored from a snapshot, but often times it hasn't finished restoring the entire snapshot by the time your workflow runs, so IO can be very slow, even if you don't need to read from the still-frozen parts of the disk. Some software ran inside workflows will do heavy R/W on C: drive, but it's better to move anything that will be written to disk, e.g. caches, to D: if possible. This often leads to much better performance with I/O and more predictable runtimes, particularly when there isn't a lot of actual compute to do.