Small executable vs less memory utilization

Pseudo code:
For i = 1 To Len("testing") '1 instance of "testing"
 MsgBox(Strings.GetChar("testing", i)) '2nd instance "testing"
Next

Question(s):
Let's say that instead of "testing" we use a 2000 page book.  Our executable would be decently large, mainly in part to the redundancy of the code.  Consider: If the variable were dimmed, that would effectively cut the size of the executable in half.  The repercussion is a 2000 page book would then be stored in memory (I'm guessing).

So I ask the following:
1. A)  Is "testing" stored in memory anyway?
Here's what I think might happen:  Yes, it is stored, but it is disposed immediately after use.
1. B)  The 2000 page book would be stored, then deleted, then stored again if it were not dimmed, right?

2. A) If it is not stored in memory and, instead, used only as needed by the processor; which would be faster code; dimming or not dimming (the processor is quicker than memory referencing, right?)?
2. B) If it goes directly from code to the processor when it's undimmed then it seems faster to not dim certain variables.  Is dimming, then, only for the sake of preserving hard drive space?

Now I know dimming is better for calculations when referencing a result repeatedly (i.e. x = 1+1 is less processor intensive than 1+1 every time you need it).  It's a lot easier to reference an address for a value than to have the CPU perform complex functions repeatedly.  However, in a specific scenario such as this, which is better AND how does it actually work?