Aren't misaligned pointers (in the BEST possible case) supposed to slow down performance and in the worst case crash your program (assuming the compiler was nice enough to compile your invalid c program).

Well, the following code doesn't seem to have any performance differences between the aligned and misaligned versions. Why is that?

/* brutality.c */

#ifdef BRUTALITY
    xs = (unsigned long *) ((unsigned char *) xs + 1);
#endif

...

/* main.c */

#include <stdio.h>
#include <stdlib.h>

#define size_t_max ((size_t)-1)
#define max_count(var) (size_t_max / (sizeof var))

int main(int argc, char *argv[]) {

    unsigned long sum, *xs, *itr, *xs_end;
    size_t element_count = max_count(*xs) >> 4;

    xs = malloc(element_count * (sizeof *xs));
    if(!xs) exit(1);

    xs_end = xs + element_count - 1; sum = 0;

    for(itr = xs; itr < xs_end; itr++)
        *itr = 0;

#include "brutality.c"

    itr = xs;
    while(itr < xs_end)
        sum += *itr++;

    printf("%lu\n", sum);

    /* we could free the malloc-ed memory here */
    /* but we are almost done                  */
    exit(0);
}

Compiled and tested on two separate machines using

gcc -pedantic -Wall -O0 -std=c99 main.c
for i in {0..9}; do time ./a.out; done