Hilmar,
>> Technically, this is correct. However, I think Visual FoxPro has to do the
>> following to get variable "x":
>> 1) Find RAM-location of variable "x" in a list of variables. This is
>> the "lookup" i was referring to.
>> 2) Fetch the variable from the location it found.
>>
>> Step 1 is the slower of the two, and a compiler (i.e., one that treats
>> variables as a compiler usually does) would only do step 2.
Variables and constants of one form or another are usually stored in a data-structure called a symbol table. This can be represented in a couple of ways but is most commonly implemented as one or more B-Tree's so lookup is extremely efficient.
You can do some extremely clever things with intermediate code and symbol tables that can make this process almost as fast a native code image, I doubt its something that you could easily measure (or would even want to!). Try the following link for more information.
http://compilers.iecc.com/faq.txt