Varying speed of a program.

[matalog]

I have been trying to measure how long a program takes to run using TICK:

Code:

T1:=TICKS

CODE

T2:=TICKS
PRINT(T2-T1).

Which seems to do what it says it will.

The problem is that it is different every time I run the program it returns a different length. There is no random WAIT() or anything that I would have thought would vary the runtime of the program.

Any Ideas what causes the program runtime to change?

To give an idea, it has been varying between 51 and 42 seconds for one program, and between 55 and 50 seconds for another. It seems to run fastest when the calculator has just been turned on.