Two versions of code with a slight difference. One is faster, but why?

[Cosmos75]

I have two versions of code with a one difference. Below are the only lines of code that are different.

[COLOR=Green]'-----------------FAST-----------------[/COLOR]
Xmultiple = 0
M = Limit ^ (i - 1)
While Xcurrent  > G
    Xmultiple = Xmultiple + 1
    Xcurrent  = Xcurrent  - (M)
Wend

[COLOR=Green]'-----------------SLOW-----------------[/COLOR]
M = Limit ^ (i - 1)
Xmultiple = (Xcurrent  - G) / M
Xmultiple = CInt(Xmultiple + 0.5) [COLOR=Green]'RoundUP to 0 decimals[/COLOR]
Xcurrent  = (Xcurrent  - (Xmultiple * M))

Why is the second version slower?


The faster version takes anywhere from 66% to 91% of the time the slower version takes to run (based on the total time it took to run several thousand test runs, which I did several times).

One more piece of info on the code that may or may not be useful.
- “Xmultiple ” will never be more than "Limit", therefore the number of times the faster code will loop though the While statement will also never be more than the value of "Limit".

 

[Fizzio]

I hope that this is not a test

Couple of simple observations.

• Less Nesting of brackets - despite having a loop, mathematics are a lot more simple.
• No call to built in functions (CInt)

You may of already done this but explicitly defining your variables will shave off a little more time as well.

 

[KenHigg]

I concur: CInt() is the main culprit...

kh

 

[Cosmos75]

Fizzoi.

I hope that this is not a test

You lost me there...

Couple of simple observations.

• Less Nesting of brackets - despite having a loop, mathematics are a lot more simple.
• No call to built in functions (CInt)

My thanks to you for clearing that up for me!

You may of already done this but explicitly defining your variables will shave off a little more time as well.

Yes, I did do that. And I'll admit that I sometimes forget but I am trying to get in the habit of using Option Explicit to help remind me to declare all my variables.