> Do you have anything more interesting than fmt="%s" ?
and
> It seems to me that the proposed changes are too tricky and too dirty for such a modest gain.

To be honest, I didn't write dont_overallocate.patch to speed up formatting strings, but it's a patch to prepare another change on str.format. The patch limits the overhead of _PyUnicodeWriter for str.format.

I proposed the change as a separated patch because I prefer simple patches: they are easier to review and to benchmark. But I agree the speed up is less impressive :-) I also prefer small patches for practical reasons. It's not easy to exchange huge patches on the tracker and to manipulate them. I always hesitate to start a new HG repository for a specific issue.

I will rewrite my format_writer-2.patch based on dont_overallocate.patch. It looks like you are waiting for the full patch.