We have a large project that is entirely coded in ASCII. Is it worth putting coding statements at the beginning of each source file (e.g. #coding=utf-8) for some reason if the source doesn't have any unicode in it?
Thanks,
--Peter
You should do one of two things (at least):

Add a hook to your repository making it verify on checkin that all python files are still pure ASCII.
Put the explicit ASCII-encoding tag in the files.

You might want to check if you get significantly better startup when the explicit tag is UTF-8 though. Anyway, I would consider that a bug of the interpreter.
This way, if anyone slips and mistakenly adds some non-ASCII characters, you won't have to chase that (potential) bug. Explicitly restricting to ASCII has one advantage: You actually can reliably see what each string contains and there are no equal-seeming distinct names.
If your source is ASCII, should you specify coding?