Re: Why does adding a useless copy-sequence and discarding the result make my ELisp 40 times faster?

[Stephen Leake <stephen_leake@stephe-leake.org>]

Clément Pit-Claudel <cpitclaudel@gmail.com> writes:

> I can't make sense of the following three observations: adding a
> useless (copy-sequence …) and discarding the result makes my code
> roughly 20-times faster, sending strings of length 2^16+1 to a
> subprocess is several times slower than sending strings of length
> 2^16, and sending 2^6 strings of length 2^10 is much faster than
> sending a single string of length 2^16.

I have also seen weird timing behavior with subprocess communication.

One thing to check; are you using a pipe or a pty? To use a pipe, do:

(let ((process-connection-type nil))
    (start-process ...))

There's also make-process in emacs 25, which has an arg for this.

--
-- Stephe