Re: STL slower than C
tohava <tohava@gmail.com> wrote:
On the thread regarding C and C# performance, Rune Allnor said:
The STL is a compromise between ease of use, safety and
functionality.
It is well known that the run-time performance of the STL can be
beaten by traditional C-style constructs. It is up to the coder to
balance the conveniences offered by the STL against the raw
performance of more 'primitive' coding styles.
I was wondering, can anyone give examples of specific cases which
demonstrate STL slowness in comparison to C. I'm also curious as to
which programming idioms can improve STL efficiency. Note that I feel
that we should separate between cases where the compiler supports
Rvalue-references and cases where it doesn't, since these probably
also have a major effect on container efficiency.
I got into an argument about this with a work mate of mine. He insisted
that he could write a custom linked list in C for our application that
was faster than the STL list class. I asked him what evidence he had for
this assertion and all he could come up with was that of course his code
would be faster, because of the reasons you cite above while his code
would be highly optimized for our particular situation.
A challenge ensued and the winner was the STL list class. It was a full
5% faster than anything he could come up with, even when he tried asm
optimizations.
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