On Thursday, 1 April 2021 at 19:55:05 UTC, H. S. Teoh wrote:
On Thu, Apr 01, 2021 at 07:25:53PM +0000, matheus via
Digitalmars-d-learn wrote: [...]
Since this is a "Learn" part of the Foruam, be careful with
"-boundscheck=off".
I mean for this little snippet is OK, but for a other projects
this my be wrong, and as it says here:
https://dlang.org/dmd-windows.html#switch-boundscheck
"This option should be used with caution and as a last resort
to improve performance. Confirm turning off @safe bounds
checks is worthwhile by benchmarking."
[...]
It's interesting that whenever a question about D's performance
pops up in the forums, people tend to reach for optimization
flags. I wouldn't say it doesn't help; but I've found that
significant performance improvements can usually be obtained by
examining the code first, and catching common newbie mistakes.
Those usually account for the majority of the observed
performance degradation.
Only after the code has been cleaned up and obvious mistakes
fixed, is it worth reaching for optimization flags, IMO.
This is my experience as well, and not just for D. Pick good
algorithms and pay attention to memory allocation. Don't go crazy
on the latter. Many people try to avoid GC at all costs, but I
don't usually find it necessary to go quite that far. Very often
simply reusing already allocated memory does the trick. The blog
post I wrote a few years ago focuses on these ideas:
https://dlang.org/blog/2017/05/24/faster-command-line-tools-in-d/
--Jon
