Maybe it would be appropriate to distinct between this, these and some.
These, as referring the program that titles the thread. Why? It gives you a set of options and says "Click here to optimize x", "Click here to optimize y", then press "Apply", and your computer will go faster. Whoo, and the program did, what? Optimize hard disk -> Disable registering last access (I guess), that it's a good thing for performance, but if you use temp files cleaners, we have a problem. Optimize processor -> Set the size of the L2 cache in the registry (a classic), that does absolutely nothing. Oh, and it prevents from getting miselanious cookies, great.
Perhaps I'm being a bit harsh, but I know these programs since a long time, at the turn of the millennium, tweaking Windows was the coolest thing ever, and the net was blooming with these apps, that did absolutely nothing, or totally obscured what they did, something that pissed me off. Of course, there are apps that gives you access to system tweaking, but without using empty tricks and telling you what are they going to do, and they're highly useful for various things, not only for making Windows run "faster". A good example? TweakUI or the same XPConfig that lanux mentions.
I understand cmpm concerns and we're not criticising you, but only giving some warning about possible problems that such software could inflict on Windows. I mean, in Curt's case, it brought the whole system down