Benchmark suite can fail unexpectedly

[konn]

We have a really nice benchmark suite to ensure efficiency. However, in some (unpredictable) cases, it fails due to an unexpected resource busy exception, e.g. see Benchmark #630.
Since the current benchmark suite is the most time-consuming part of a CI, which can take up to two hours, and it can unexpectedly fail at the very end of a run, it might be favourable to avoid such resource busy exceptions.

[pepeiborra]

I have a fix and other improvements coming