It seems to be inevitable that a computer running a Windows based operating system will slow down over time.There may be numerous reasons why your computer behaves badly and is no longer the speed demon it once was. Simple maintenance, practiced regularly, which is easy even for a non-expert, can keep your Windows based PC running smoothly at peak performance for years.

The most common problems that have impact on a computer’s speed and behavior are listed here, with the appropriate free software solution. This is not however, an exhaustive list.
In most cases, since a slow computer is generally being impacted by more than one problem, you will probably find that you will have to resolve the issue using more than a single solution.

Too many programs loading on system startup is a common cause of longer than normal boot up times.
Solution: WinPatrol

Using WinPatrol you can monitor your startup programs and services, cookies and current tasks. Should you need to, WinPatrol allows you to terminate processes and enable, or disable, startup programs. There are additional features that make WinPatrol a very powerful addition to your utility toolbox.
Fast facts:
Decrease CPU Usage and Conflicts
Express boot option
Download at: Download.com
A jam-packed, jumbled registry can be one of the chief causes of computer slowdown and malfunction. A messy registry can often put a brake on your system, cause programs to stop working properly, and aggravate you while you hang around waiting for the operating system to load at a snails pace.
Solution: Regseeker

Many applications, on being uninstalled, leave behind “orphan” registry entries. They don’t remove all traces of themselves; causing problems such as sluggish performance, system lockups, or a bloated registry that takes longer to load on startup. With the click of a button, Regseeker will scan your registry for these fragmented files, and safely remove them.
Fast facts:
Scans and cleans your registry
Multifunctional
Performs tweak operations
Clean out your startup entries
Add/Remove program entries
Adjust color schemes
Change personal information entries
Download at: Download.com
Disk fragmentation, especially on intensively used systems, will degrade performance over time. This is a good task to automate by using a third-party tool.
Solution: Auslogics Disk Defrag

The program is extremely easy to use, does not require any analysis phase and is faster than most disk defragmentation software I’ve tested in the past, and it’s free. In my view, it’s one more maintenance process in helping me get the maximum performance out of my hardware.
Fast facts:
Improve computer performance and stability
Increase your productivity - no more waiting for files to open
Defragment disks in minutes
Disk fragmentation map and detailed fragmentation report
Download at: Download.com
Your Hard Drive is full.
A full Hard Drive will not function efficiently since you require at least 2 - 3MB of free space for programs to run smoothly. If you lack this much free space, you should uninstall unused programs on your primary drive.
Solution: Revo Uninstaller

Revo Uninstaller is a superior program to uninstall programs from your computer. This free program with its advanced and fast algorithm scans before, and after you uninstall an application. After the program’s regular uninstaller runs, you can remove additional unnecessary files, folders and registry keys that are usually left over (those “orphaned” registry entries we talked about earlier), on your computer. This feature is a definite plus.
Fast facts:
Superior uninstaller
Free
Fast algorithm scans before, and after uninstall
Removes additional unnecessary files, folders and registry keys
Download at: Download.com
Running a Disk Cleaner will help to optimize your system by emptying the Recycle Bin, Temporary Setup Files, Downloaded Program Files, Temporary Internet Files, Old Chkdsk Files, Temporary Files, Temporary Offline Files, Offline Files, and so on.
Solution: CCleaner

For a full and through cleanup, I highly recommend CCleaner. As well, you should consider copying archived files such as pictures and music, to CD’s or DVD’s to free space on the Hard Drive.
Fast facts:
Frees up valuable hard disk space
Advanced features to remove unused and old entries
Comprehensive backup feature
System tray icon
Privacy tool
Download at: Download.com
Your Internet connection is slow.
Even the fastest Internet connection is a lot slower than any relatively modern PC, so make sure your Internet settings are properly optimized.
Solution: Ashampoo Internet Accelerator 2

Ashampoo Internet Accelerator is a great little application that makes it easy to perform this simply task. Ashampoo Internet Accelerator 2 is an excellent free Internet connection optimizer.
Fast facts:
Free
Fully automatic
ISDN, DSL via LAN cable or cable modem, DSL via wireless LAN
Improvements in performance connection
Download at: Download.com
Malware Infections.
It’s possible of course, that the performance of your computer has been adversely affected by malware infections. If you believe that’s the case, read my article on this Blog, “Need Free Security Programs? – 10 of the Best!”
Once you have removed system-clogging clutter, ensured your Internet settings are properly optimized, are satisfied your system is not infected with malware, and performed the other simple maintenance, your PC should satisfy you with its capabilities.