My single last concern is what I wrote earlier: "Flags 2 and 3 are a bit tricky: Actual bailing
will uglify the code and make it much more complicated so I would prefer in practice to just
check up front with a good metric whether the possibility to be non-performant is high and in
these cases just not call the checker at all."

If we agree on this one, I am gonna wrap it up in the next 2 days. :-)