Patch Set 1: Looks good to me, but someone else must approve; IP review completed

I agree also that we should remove this kind of test from our standard tests unit tests executed always. And of course its much better to test with real data instead of generated test data like here.

There is one aspect for which we can enrich debug-diff-algorithms to cover what we delete here. DiffPerformance test did not "test" the absolute performance of a diff algorithm but tested how much the overall runtime increases if we increase the size of the diffed texts. Just to see whether we are working with O(n*n) or O(n*log(n)) or something different. Would be nice to have
such tests also for real data.