CREATE A XREF IN MAXSCRIPT

I make a script create a xref with a name , everything is ok , but the " xrefs.addNewXRefObject " is too slow , i dont know why ? can you fix it ?

rollout xrefmng "XREF"
(
edittext txtName "NAME" text:"NewName" width:130 height:18
button obj2xr "OBJ to XREF"
on obj2xr pressed do
(
disableSceneRedraw()
newpath = maxFilePath + "xref/"
makedir newpath
filepath = (newpath + txtName.text+".max")
if $ != undefined do
(
saveNodes $ filepath
delete $
)
----------------------------------------
objNames = getMAXFileObjectNames filepath
xrefs.addNewXRefObject filepath objNames dupMtlNameAction:#useScene
enableSceneRedraw()
)
)
createdialog xrefmng