Not to sure whether to give a 5 or a 1

I restarted my computer and had no apps running other than Caffeine. I watched my available memory go from 1.5 GB to 142 MB in 5 minutes and I was doing absolutely nothing on my computer. I would like to understand why this is happening. Makes the app feel a little like the the wizard in the Wizard of OZ hiding behind a screen. Perhaps the developer can explain this.

didymush about Memory Booster - RAM Optimizer