One other thing you should check for periodically are duplicate files. These may accumulate over the years as you make ad-hoc backups, re-install software that may use a different location to store data, or download the same stuff inadvertently. A good duplicate file finder such as Auslogic's Duplicate File Finder or Nirsoft's SearchMyFiles is all you need for this. They're both free.
Disable background apps you don't use
As I mentioned, even useful software will install and run stuff you don't really need. For instance, Java and Adobe install updaters that continually suck CPU cycles and slow your boot times. If your Java is out of date, your browser or Java apps will let you know. Adobe, Apple, Intel, and others love to install background applications that help their software load faster or assist in some other way. If it's for a piece of software you use regularly, it may be worth it. If not, you might want to disable it.
To disable a background app, run msconfig.exe in Windows XP or 7 or the task manager in Windows 8, and select the Startup tab. Once again, searching online for information may be required to find out what's useful and what's not. Some programs still use the Startup folder on the Start Menu, so you can remove items from there as well. There's no undo as with the Startup tab, so while you're only removing a shortcut, it pays to be a bit more careful with the Start Menu.
Note: Adobe Flash is an oddball: You must log on to the company's website to stop it from automatically updating itself.
Back in the days of FAT16 and FAT32, defragmenting files made a noticeable difference in hard drive and system performance. But with the advent of NTFS, faster CPUs, and more memory, defragging your hard drive is rarely necessary, and the difference may not be noticeable.
That said, an occasional defrag isn't going hurt--once every six months should do it. Windows 8.1 elects to automatically "optimize" (defrag and rearrange files) your hard drives on a weekly basis. I'd argue for my semi-annual schedule, but as long as it's not happening while you're trying to work, it's no big deal. All this is done via the Optimize Drives dialog in Windows 8.1. Older versions of Windows require right-clicking on a drive icon, selecting Properties, then Tools, then Defragment Now.
The Windows defragger is more than adequate, but there are numerous third-party replacements such as Auslogic's Disk Defrag, IObit's Smart Defrag 3, and Piroform's Defraggler. They purportedly work better by offering more control over where files are placed. I've used or tested them all, and all work well. Is there a discernible difference in the results versus the Windows defragger? Maybe on an old, slow system, but I sure can't tell the difference on mine.
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