[Closed] map channel to edit normals : need speed

Hello there,
So, i’m trying to convert a map channel to vertex normals.
It works, but it’s slow (94sec for the sample file), and the time it takes is exponential. I guess there’s a lot of place for optimization.For instance, all polyop in the loop…
I upload a sample mesh here (max 2012)
https://dl.dropboxusercontent.com/u/13762052/cgtalk/mesh_normals.rar
I used bits from DenisT…

      chan = 4
      tObj = $		
      
      time01 = timestamp()
      
      --return a tvert.pos from vert
      fn getMapPos node chan vert =
       (
      	-- if not polyop.getmapsupport node chan do polyop.setmapsupport node chan on
      	f = ((polyop.getfacesusingvert node vert) as array)[1]--get only 1 face used by vert
      	vv = polyop.getfaceverts node f 
      	tv = polyop.getmapface node chan f
      	id = tv[finditem vv vert]
      	polyop.getMapVert node chan id
      )
       
      normal_array = #{}
setCommandPanelTaskMode mode:#modify
      collapseStack tObj
      mod_normals = Edit_Normals ()
      addmodifier tObj mod_normals
      
      _ConvertVertexSelection = mod_normals.ConvertVertexSelection 
      _Setnormal = mod_normals.Setnormal 
      
      numNorm = mod_normals.GetNumNormals()
      mod_normals.SetSelection #{1..numNorm}
      mod_normals.Unify()
      mod_normals.MakeExplicit()
 
      for i=1 to tObj.numverts do 
 (
 	normVal = getMapPos tObj chan i
 	disableRefMsgs();
 	_ConvertVertexSelection #{i} normal_array	
 	normID = (normal_array as array)[1]--get 1 normal for the vert
 	_Setnormal normID normVal
 	enableRefMsgs();
 )
 update tObj
 
 time02 = timestamp()
 gc()
 
 format "took % 
" ((time02-time01)/1000)

  On my channel 4 stand all my normals vector. Each face is exploded (result from a projection from another mesh). I can't weld them because obviously i lose the .z information.
  I only have 1 normal per vertex, so i thought i could make small optimisation by looking in only 1 mapface.
  
  Thanks for hints !

Edit: ok, with
disableRefMsgs();
enableRefMsgs();
It takes 6 sec instead of 94.