Re: master afc0bfd380: Speed up loaddefs-generate on slow disks

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> This suggests that the kind of change I suggested would make it even
>> a bit faster, tho it should reduce the run time by less than 50%
>> under Windows (because the time to do the `stat`s is apparently already
>> >50% of the total).
>
> I don't know how you deduce the 50% figure.

The old code performed 2*N `stat`s.
The new current code performs N times `time-less-p` and
`file-attributes`, which is N `stat`s plus N times some overhead.
The proposed new functionality would reduce this to more or less just
N `stat`s so it would save us the "some overhead".

Because the old code is slower than the current code, we know that

    2*stat > stat + overhead

thus `stat > overhead`.  So `overhead` is less than 50% of `stat + overhead`.


        Stefan