My understanding was that using the "selection" command slows down code, my
ideas was to use it only once and put answer in memory then use that on a
select statement, would the processing speed between that and your code below
be negligible? I could be going through 10,000 records.

Whilst some would claim otherwise, you could use:

Select Case True
Case Selection Like "A*"
Selection.FormulaR1C1 = "AL"
Case Selection Like "G*"
Selection.FormulaR1C1 = "GL"
...etc