Suspicious or no, I have been using this program for a bit, a few years. The thing is, is that it's highly customizable, and in fact will depend completely on user-defined settings towards what it will and will not close.
Here's the basic breakdown.
You open the program, and then you can configure which unnecessary background programs you want temporarily closed, as well as services, Windows components that tend to do rather arcane and advanced things you won't be using when playing a video game, if at all. You then push the ginormous button, and the program closes the list of processes you selected, along with the services.
I find that the services don't actually take up much RAM, maybe 10-50ish MB, but closing the unnecessary programs can free anywhere from 50MB RAM to 300MB RAM, depending on what I'd previously opened.
Then, when you're done playing, you push the button again, and it restarts everything again for you, all the processes and programs.(My personal list of closed programs includes the java updater, webcam services, unlocker assistant, Adobe Acrobat assistant, several tray icon programs, iTunes Helper, Daemon Tools Lite, Download Managers, Registry Mechanic, Advanced SystemCare, OpenOffice QuickStart and a router driver)
The effectiveness really depends on how much your programs are already using. If you have a rather low-end system, and not much memory to spare, say a GB of ram, 1024MB... then freeing up that 300 can make the difference between 30DFPS and 100. Higher end systems that get bogged down with programs may also benefit, if, say, all your Windows and background crap is hogging around 700MB RAM, maybe even 1.5GB of RAM with some antivirus clients and downloaders, then closing all that -- temporarily -- can give you back more of your, say, 4GB of RAM. This also would include all those services and all the programs that would have been bureaucratically using your CPU, for worthless administrative crap for your computer.
All that CPU power and RAM would now instead go towards simulating that 10Z-level waterfall you made!
Also...
Some of these you can disable by hand and some I personally cant run without, not sure how's your comp set up. I personally do not trust any "cleanse ram and make your comp run faster" programs because if it work so easily microsoft would have implemented it already About the only thing they dont do is overclocking.
Well, yes, some things you really need. That's why you can SET the parameters. And Microsoft isn't really the best example as regards to tech-and-user support. You depend on THEM for your computing needs, and you're... kinda screwed.