Modules & VBA :: When To Use Global Variable

I have an application where several different procedures are run repeatedly every xx seconds to get live updates from a server (different procedures depending which form the user currently has open.) Within each procedure, a separate single procedure is called only if a stored boolean setting is set as true. The setting itself is only changed very infrequently, such as on application startup, but needs to be initially set (i.e. it cannot just have a default of False if it is not set.)Because of this I am storing the setting in a single record table and have a function 'UsingWPilot' to return the boolean value. However, given the frequency that the setting needs to be accessed, and the fact that speed is crucial in the running of the app, I am considering adding a global string variable and modifying the function to look at the variable (possible values 'N' and 'Y') and only going to the table if the variable has not been set.

I have heard various things about how you should never if possible use global variables. My question is: is it faster to use a global variable than to open the table record each time?

option 1 :

Code:

Public Function UsingWPilot() As Boolean
Dim db As DAO.Database
Dim rs As DAO.Recordset
Set db = CurrentDb
Set rs = db.OpenRecordset("rbl_Settings_System")

Option 2:

Code:

Public Function UsingWPilot() As Boolean

Dim db As DAO.Database
Dim rs As DAO.Recordset
If Len(g_WPilot) > 0 Then
UsingWPilot = (g_WPilot = "Y")
Else
Set db = CurrentDb
Set rs = db.OpenRecordset("tbl_Settings_System")

[code]....