Martin v. Loewis writes:
into the code. In an application that almost exclusively does COMPARE_OPs on identical strings, I got a 30% speed-up. OTOH, this same code caused a 10% slowdown if I converted the "==" into "<>".
It's very questionable whether we'll find an optimization that works well for any serious variety of applications. Perhaps there's some way to build up a lookup table of fast paths, and have the slow path try that first, but I'm sceptical.
Running the PyXML test suite, I counted 120000 cases where slow_compare was done, and only 700 cases identical strings were compared for equality.
I wouldn't expect XML applications to gain from such an optimization, since many compares will involve Unicode objects, either to each other or to 8-bit strings.