Comparative benchmarks [Feature]

[sfmig]

We consider two types of benchmarks:

• We run absolute benchmarks on our internal runner, using user-representative datasets. These benchmarks will run regularly and the results will be published to a static site.

• We run relative benchmarks on CI with small data. This is useful to detect if a PR introduces performance regressions. We plan to follow an approach similar to the one proposed here.

We first plan to implement the first type, but it would be very useful to have a go at the second one too.