According to the title of your thread, Max, you posted : Keeping Windows Lean and Mean
I took that as how does one go about keeping their Windows (what ever flavor you desire xp, vista, 7, 8, 8.1, 10 etc) with a properly installed OS that has been properly tweaked, more specifically lean/cleaned registry and services & processes tweaked etc...
I would have recommended you to go check out BlackViper.com, but his website has been down for sometime now, after going down roughly a 1/2 dozen times intermittently over he past 2 or 3 years..
I can tell you to definitely not try to clean up / tweak your OS by using msconfig! you should always use services.msc <---- SPECIAL NOTE: Do not go messing around in services until you have read up on the subject, researched it and fully understand what each service does as well as what each particular service might be a dependent of or what service might depend on the service you are currently looking at
as for using a program like "CCleaner",I myself prefer to clean up "my own OS" ( processes, services, registry, startup,etc ) the manual way, without installing/using PC fix'em tool programs, YMMV so to each their own
hope this helps
TC