more optimising

[n1ghtowl]

im still trying to optimise my app.(it is deeling with bignumbers) I found something that would make a big speed difference but im having trouble understanding the code enough to impliment it. It doesn't help that the person that wrote it didn't comment anything.
I want to move the first call texttobignumber out of this sub and call it only when teststring1 changes. however it seems other subs are using the same variables and arrays. I know this meens adding another array but everytime I start trying to follow this code I get lost any help would be greatly appretiated.

Public Sub divide_nums()
Dim a(MaxLength) As Long
Dim b(MaxLength) As Long
Dim c(MaxLength) As Long
Dim d(MaxLength) As Long
Dim LengthA As Long
Dim LengthB As Long
Dim LengthC As Long
Dim LengthD As Long
Dim dumbnum As String
 
Call TextToBigNumber(teststring1, a, LengthA) ' this one needs moved out of this sub
 
Call TextToBigNumber(numtotest, b, LengthB)
Call DivBSigned(a, LengthA, b, LengthB, c, LengthC, d, LengthD)
dumbnum = BigNumberToText(c, LengthC)
remainder = BigNumberToText(d, LengthD)
End Sub

the rest of the affected code is attached including the module with the above Sub.
thank you