You could have answered your own question by writing a simple benchmark 
Code:
Break ON
$iIterations=999999
$aLoops="For $$i=1 to $iIterations Next",
"While $$i<$iIterations $$i=$$i+1 Loop",
"Do $$i=$$i+1 until $$i=$iIterations"
For Each $sLoop in $aLoops
"Benchmarking "+Split($sLoop)[0]+@CRLF
$iStart=@TICKS
$i=0
$=Execute($sLoop)
$iEnd=@TICKS
"Start: "+$iStart+@CRLF
" End: "+$iEnd+@CRLF+@CRLF
" Time: "+(CInt($iEnd)-CInt($iStart))+" ms"+@CRLF+@CRLF
Next
Exit 0
