In the course of tracing a memory leak using libxml2 via its Perl interface,
XML-LibXML, I stumbled across the fact that xmlDocDumpMemory() runs incredibly
slowly on Win32 compared to Linux.

The Perl memory leak involved repeatedly parsing and then dumping in memory a
set of 4 particular XML files.  The following C program, using libxml2 directly,
does essentially the same thing:

#include <stdio.h>
#include <time.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
int main(void) {
  xmlDocPtr doc;
  xmlChar *result = NULL;
  int i, len = 0;
  char *files[] = {
    "4M UNIBODY FODEN 4000WB.drg",
    "IVECO 130E18K 3M UNIBODY (3).drg",
    "IVECO 130E18K 13T MULTISPREAD.drg",
    "IVECO 340E38H-TRANSVERSE+2x3 HOTBOX.drg"
  };
  time_t start, end;
  while (1) {
    time(&start);
    for (i = 0; i < 4 ; i++) {
      if ((doc = xmlReadFile(files[i], NULL, 0)) != NULL) {
        printf("%d - OK\n", i);
      }
      else {
        printf("%d - NOT OK\n", i);
      }
      xmlDocDumpMemory(doc, &result, &len);
      if (result != NULL) {
        printf("%d - OK\n", i);
        xmlFree(result);
      }
      else {
        printf("%d - NOT OK\n", i);
      }
      xmlFreeDoc(doc);
    }
    time(&end);
    printf("Took %d seconds\n", end - start);
  }
}

When I ran this program I found that there does not appear to be any memory
leak, but each time around the while() loop takes about 24 seconds.  Petr Pajas,
looking into the Perl memory leak for me, tried the above program on his Linux
machine and found it takes only 1 second each time around the while() loop.

If I remove this section from the program:

      xmlDocDumpMemory(doc, &result, &len);
      if (result != NULL) {
        printf("%d - OK\n", i);
        xmlFree(result);
      }
      else {
        printf("%d - NOT OK\n", i);
      }

then my times drop to about 1 second.  On the Linux machine, the program only
became very slightly quicker.

Thus, it appears that xmlDocDumpMemory() runs very slowly on Win32.  Whether or
not this is related to the memory leak in the Perl code on Win32 (which couldn't
be reproduced on Linux, btw) is hard to say, but it would make a huge difference
to my real software if the slowness of xmlDocDumpMemory() on Win32 could be
rectified.

Here is a link to the thread discussing the Perl interface memory leak, if you
are interested: http://marc.theaimsgroup.com/?t=108928189600002&r=1&w=2

If you want the actual 4 XML files that these results were produced with, they
are available on an FTP site.  Please e-mail me for login credentials.