function blitz3d is slow than call a dll function

yes is more slow i am surpraise, this is the code in dll

// Sumar
BBDECL int BBCALL sumarwithdll( int n )
{
return n+1;
}
sumarwithdll%( n% ):"_sumarwithdll@4"


and this code is the test

; pruebas de tiempo con las dlls

Print "Pulse una tecla para empezar"
WaitKey

i = 0
nStart# = MilliSecs()
For n = 0 To 20000000
i = sumarwithblitz3d( i ) ; (blitz3d)
;i = sumarwithdll( i ) ; (dll)
Next
nEnd# = (MilliSecs() -nStart#) /1000.0

Print "Ha tardado: " +nEnd#
WaitKey

; this function is equeal at sumar of dll
Function sumarwithblitz3d%( n% )
Return n% +1
End Function

the result if you change (blitz3d) and (dll) is this
with blitz3d elapse in seconds is 9.001
with dll eplase in seconds is 4.44

is very strange