Could you post the output from the following on one machine that gives good results and one that gives bad:

#! perl -slw
use strict;
use Time::HiRes qw[ gettimeofday time ];

use Win32::API::Prototype;

ApiLink( 'kernel32', q[
    BOOL QueryPerformanceCounter( LARGE_INTEGER *lpPerformanceCount )
]) or die $^E;

ApiLink( 'kernel32', q[
    BOOL QueryPerformanceFrequency( LARGE_INTEGER *lpPerformanceCount 
+)
]) or die $^E;

sub int64_to_NV {
    my( $lo, $hi ) = unpack 'VV', $_[ 0 ];
    return $hi * 2**32 + $lo;
}

my $frequency = ' ' x 10;
QueryPerformanceFrequency( $frequency ) or die $^E;

print 'Counter changes ', int64_to_NV( $frequency ), ' times/second';

for ( 1 .. 10 ) {
    QueryPerformanceCounter( $frequency )or die $^E;
    print 'QPC: ',int64_to_NV( $frequency );
}


printf "GToD: %.8f\n", scalar gettimeofday() for 1 .. 10;
printf "Time: %.8f\n", time() for 1 .. 10;
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