"It is simple yet has a lot of customizable options through text files and scripts via two mouse-clicks. Not only is the defragmentation super fast, but also you are not going to notice it's working!
You can keep doing your things while UltraDefrag does what was born to do… defrag. It performs so well you gonna want to carry it in your wallet. A lot of varied boot defrag commands. If your goal is to optimize your system startup at maximum, this is what you need."
What's it for? - Defragmenting your hard drive on a regular basis is a sound housekeeping habit. It can greatly increase system performance and relieve stress on your hard drive.
Analyze disk space; find space hogs.
Detect duplicate files.
"Quickly and effectively remove unused or temporary files, unwanted cookies, and other unneeded files from applications." Chosen for Gizmo's 9 great freeware.
Additionally, it can scan the registry for issues, erase, manage the startup, uninstall, and clean system restore points.
Related: Also runs automatically at startup or as a task.
What's it for? - Over time unnecessary files accumulate, which can be removed with a disk cleaner to maintain system performance.
Investigate your system: view active processes, end processes, view resource use of processes, and much more.
The Windows control panel has limited uninstalling capabilities, but freeware programs like Revo and ZSoft allow for better deletion of programs by removing many files and registry entries that are usually left behind.
"To decrease the likelihood of causing problems, it allows you to backup the registry before you start and (by default) ignores areas where most registry tricks are played. I caution against changing the default settings unless you have a good understanding of the registry and how applications use it."
What's it for? - The effectiveness of registry cleaning is controversial and can lead to the need to completely re-install windows, but for computer savvy users it may help reduce potential conflicts from the leftovers of a few kinds of uninstalled software.
"Highly effective at wiping the free space, leaving behind only unrecoverable nonsense file names on modern size hard drives. It erases the unused disk space (or "free space"), cluster tips (or "slack space"), individual files or folders, and data in the recycling bin."
What's it for? - Normal file deletion doesn't prevent a common file recovery program from recovering your files, so eraser utilities are helpful to permanently delete any personally identifiable or unwanted files to protect your privacy.
"This utility, which has the most comprehensive knowledge of auto-starting locations amongst all the startup managers, shows you what programs are configured to run during system bootup or login, and shows you the entries in the order Windows processes them. These programs include ones in your startup folder, Run, RunOnce, and other Registry keys.
You can configure Autoruns to show other locations, including Explorer shell extensions, toolbars, browser helper objects, Winlogon notifications, auto-start services, and much more."
What's it for? - If you have a system full of programs running in the background or a start menu full of near useless tray icons, then startup managers are especially helpful for increasing system performance. Run programs when you want, not when they decide.
"an excellent system profiler that provides in-depth hardware information for Windows."
ToolWiz Care is an excellent freeware solution. The main tab called Checkup offers the one-click feature, system resource information, and some optional features. Since there is no paid version to upgrade to, all the features are functional.
What's it for? - Intended as an all-in-one PC performance optimizer and tweaker to simplify system tasks that typically require many separate specialty programs.