[Octave-bug-tracker] [bug #61365] dlmwrite performance regression (via network) between Octave version 4 and 6

[Markus Mützel]

Follow-up Comment #10, bug #61365 (project octave):

Thanks for the additional data points.

In comment #7, you showed times that were slightly different. In particular
writing to the server with version 4.2.1 seems to be about an order of
magnitude faster in comment #9 than in comment #7 (while the other timings
don't seem to differ as much).
Is one of those a typo?

Trying to track down which change might have caused that difference, could you
please try to bisect which version of Octave was the first with the noticeable
performance difference?

Just a wild guess (and I don't know why that would differently affect network
shares vs. local files):
IIRC starting with Octave 6, writing to and reading from `fopen`-ed files
translates between UTF-8 (Octave's internal encoding) and the system's locale
encoding (or more precisely, whatever is set with `__mfile_encoding__`).
Converting digits between ISO encodings (I'm guessing you're on a Latin-1
system) and UTF-8 should be a no-op and I guess it would be fast. But just to
be sure, could you please try and change the .m-file encoding to UTF-8 (only
works in newer Octave versions) and repeat the test? That would skip the
conversion step entirely.
You could change that for the current session with
`__mfile_encoding__("utf-8")` or more permanently in the preferences window.

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