Just retested using weighttp instead of ab and now got up to 90 kreq/s with "weighttp -c 100 -n 100000 -k http://127.0.0.1/empty";.
Still way to go compared to what others claim (e.g. vert.x or gwan) but since adding just some DB queries, file I/O or dynamic memory allocations already destroy the numbers, this is really just a very artificial setup for 99% of the applications anyway. Quite important for marketing, though, I guess.
