What is process.memory giving ?

Thanks a lot for this interesting answer, its very late, I appreciate this.
What I wanted to find with this question is the best way to write code.
There are at least two parameter, speed and size.
BTW, my next test used a module.
Base is an object called Blinker, which uses Interval.
Having LED1 to LED3 blinking in different frequency costs 175 blocks.
Same with function in modules takes more than 300 blocks.
Do you have a guide, something like "best architecture to save memory" ?