function GetCPUSpeed: Double;
   const
     DelayTime = 500;
   var
     TimerHi, TimerLo: DWORD;
     PriorityClass, Priority: Integer;
   begin
 
     PriorityClass := GetPriorityClass(GetCurrentProcess);
     Priority := GetThreadPriority(GetCurrentThread);
 
     SetPriorityClass(GetCurrentProcess, REALTIME_PRIORITY_CLASS);
     SetThreadPriority(GetCurrentThread, THREAD_PRIORITY_TIME_CRITICAL);
 
     Sleep(10);
 
     asm
       dw 310Fh // rdtsc
       mov TimerLo, eax
       mov TimerHi, edx
     end; { asm }
 
     Sleep(DelayTime);
     asm
       dw 310Fh // rdtsc
       sub eax, TimerLo
       sbb edx, TimerHi
       mov TimerLo, eax
       mov TimerHi, edx
     end; { asm }
 
     SetThreadPriority(GetCurrentThread, Priority);
     SetPriorityClass(GetCurrentProcess, PriorityClass);
 
     Result := TimerLo / (1000.0 * DelayTime);
   end; { GetCPUSpeed }