MS Access date range functions slowing down query - function

Question

I have a query in which I am using a between statement to pull data for a date range. I have a VBA function built, that will evaluate the last date (Max Date) in a table (to get the 1st date for the between) and another function to evaluate the stop date (last date of the between)...So my between date statement looks like this: Between hhMaxDte() And hhLastDte()
For some reason having these 2 functions in my between statement takes what seems to be 8x longer to run the query than if I just manually put the actual dates in myself. Anyone out there know why this is and how I can dynamically do a similar process, but take the same amount of time to run the query, as when I manually enter the dates? My functions code is below:
Function hhMaxDte()
If DMax("row_date", "HH_CIB_Raw_Data") + 1 = Date Then
hhMaxDte = 0
Else
hhMaxDte = DMax("row_date", "HH_CIB_Raw_Data") + 1
End If
End Function
Function hhLastDte()
If DMax("row_date", "HH_CIB_Raw_Data") + 1 = Date Then
hhLastDte = 0
Else
hhLastDte = Date - 1
End If
End Function

Answer 1

I've figured out the answer based off of the feedback in the comments above. The function was running for each row of data, thus significantly slowing down the return of the results. In order to avoid this, I used the built in function Dmax (to analyze the max indexed date in a table) and Date to create a between statement in the Access query criteria section:
Between DMax("row_date","HH_CIB_Raw_Data")+0 And Date()-1
Now the append query is able to dynamically pull data based off of the recent dates missing in the table and runs in a matter of seconds VS 2-3 min.
Thanks for all the input guys!!