include 'win32ax.inc'
.code
start:
      invoke GetTickCount
      mov ebx, eax
      xor eax, eax
      invoke GetTickCount
      sub eax, ebx
      invoke wsprintf, _buffer, _format, eax
      add esp, 12
      invoke MessageBox, 0, _buffer, "Test", 0
      ret
.end start          ;
.data
     _buffer rb 20
     _format db '%u'    

The resolution of the GetTickCount function is limited to the resolution of the system timer, which is typically in the range of 10 milliseconds to 16 milliseconds.

include 'win32ax.inc' 
.code 
start: 
      invoke GetTickCount 
      mov ebx, eax 
      invoke Sleep,1 
      invoke GetTickCount 
      sub eax, ebx 
      invoke wsprintf, _buffer, _format, eax 
      add esp, 12 
      invoke MessageBox, 0, _buffer, "Test", 0 
      ret 
.end start          ; 
.data 
     _buffer rb 20 
     _format db '%u'