usleep is not working on Windows

I'm using usleep to simulate slower internet in my projects, so to have a better perception of the screens when there is loads for ajax requests for example.

Using a linux environment seems to work normal if I use:

usleep(2500);

But in Windows seems to have no effect, the delay does not occur. I know that usleep has some problems that may vary for each processor and I even know of this alternative mentioned in the php .net # 54572 :

dl('php_w32api.dll');

$GLOBALS['win32api'] =& new win32;

// USleep alternative for Windows and PHP4:
$GLOBALS['win32api']->registerfunction("long Sleep (long dwMillisecods) From kernel32.dll");

// Now you can call the function from everywhere in your script: $GLOBALS['win32api']->Sleep(milliseconds);

for ($msec = 2000; $msec > 0; $msec = $msec - 125) {
  echo "Hi. Next one in $msec msec.\n";
  $GLOBALS['win32api']->Sleep($msec);
}

But where I read the problems are related to the differences in time and processor reaching 100%, but I did not find out about the "not working" function.

I'm using:

• Processor: Interl Core i5 m450 (2.40 GHz)
• PHP 5.4.12 (Thread Safety)
• x64 Architecture
• Server API: Apache 2.0 Handler

Is it a processor variation or the PHP version?