Hmm. I guess I didn't realise I was asking for trade secrets here.
Your example is incomplete as you don't say what string you would need to run it against for it to produce pathological behaviour.
As I've mentioned, I've produced many that take a long time to process, but I'm failing to grasp the significance of what aspects take time, and which consume stack. Maybe this should be obvious to me, but it isn't.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.