[Boost-users] Xcode - Slow

Subject: [Boost-users] Xcode - Slow
From: Raphaël Amiot (raphael.amiot_at_[hidden])
Date: 2010-06-30 11:55:46

Hello there.

I am implementing matrix multiplication and am trying to have my stuff run as fast as possible.
But then I noticed something strange. 
Using Xcode,

resultmatrix = prod(matrix1,matrix2);

is 10 to 16 times slower (with 100x100 matrixes) than simply doing something like that: 

for(...)
        for(...)
                for(..)
                        multiply_things();

And 20 to 40 times slower than a simple threaded approach.

Using visual studio, it's 2 times faster than naive multiplication.

This is on a release build, with 
#define BOOST_UBLAS_NDEBUG 1
#define NDEBUG 1

So what gives?