On closer inspection, the translator already reports peak memory usage.
It uses the same method as the search component, and hence only works under
Linux, but still it's probably not worth bothering in this case.
Probably using psutil (https://code.google.com/p/psutil/) is our best option. It
adds a new dependency, but works on both python 2.x and 3.x.
Maybe we should only print a warning instead of aborting in case psutil is
missing?