XViD Profiling Measured time != Overall time

*Dear Experts,*

Whenever I use XViD Profiling using the utils/timer.c code, the output is
like this:

Overall encoding time: 140.000000 ms, we measured 40.000000 ms (28.571429
percent) Or

Overall encoding time: 160.000000 ms, we measured 100.000000 ms (62.500000
percent) and never ever is the measured time equal to the overall time. I
have even re located the global_satart_timer and global_Stop_timer()
functions but it has not measured 100 % time. My question is if 60 % of the
time is the measured time, then where is the remaining time consumed.

_____________________________________________________________________________________

start_global_timer();
   switch(coding_type) {

    case I_VOP :

      decoder_iframe(dec, bs, quant, intra_dc_threshold);
      break;

    case P_VOP :
      decoder_pframe(dec, bs, rounding, quant,fcode_forward,
intra_dc_threshold, NULL);
      break;

    case S_VOP :
      printf(" No S-VoP Support in MPEG-4 SP Decoder ");
      break;

    case N_VOP :
      printf(" No N-VoP Support in MPEG-4 SP Decoder ");
      /* not_coded vops are not used for forward prediction */
      /* we should not swap(last_mbs,mbs) */
      /*
      start_timer(); // I made myself ; Although this is not necessary as My
input bitstream does not use this case
      image_copy(&dec->cur, &dec->refn[0], dec->edged_width, dec->height);
      SWAP(MACROBLOCK *, dec->mbs, dec->last_mbs); // it will be swapped
back
      stop_general_timer();
      */
      break;
    }

   stop_global_timer();
____________________________________________________________________________________________

Inside decoder_iframe and decoder_pframe I have included all the code into
the profiling. But still the total measured time is not 100 %. Why is this
so, and seemingly there is no apparent code where the other percentage of
time is spent. Please help me regarding this issue.

*Regards,*

Anwar Sajid
Seoul, Korea