Slow work expression with picture

[#1]

I create in QlikView expression:

  if ($1 = 0 OR IsNull($1), null(), 'qmem://<builtin>/' & 

          if($1 >= 1.5,'Arrow_N_R.png',

          if($1 >= 1.20,'Arrow_NE_Y.png',

          if($1 >= 1.05 ,'Arrow_NE_G.png',

          if($1 >= 1,'Arrow_E_G.png',

          if($1 >= .95 ,'Arrow_W_G.png',

          if($1 >= .80  ,'Arrow_SE_Y.png',

          if($1 >= .50 ,'Arrow_SE_R.png',

          if($1 >= 0 ,'Arrow_S_R.png','Arrow_S_R.png') ))))))))

where i mean $1 = SUM({SetValue} value1)/Sum({SetValue2} Value2).

Tell me please - QlikView was only one calc SUM({SetValue} value1)/Sum({SetValue2} Value2) for this expression?

Or for every ">=" was again calc?

I ask because this expression with picture work very-very slow