[wip] Benchmark

Last week during the hangout we shortly discussed adding some sort of benchmark to the ol build (as a follow up of #2360). This pull request is a first idea on how this _could_ look like.

In my WKT pull request I also added a speed test. Unfortunately, this test was quite specific to the WKT parser. We could of course run & time the tests, but I don't think this is quite reliable, without making it last forever. It might make more sense to write some specific timing tests, for example.

Well, I wanted to share my current state in this.