Is your Windows PC running a little slowly? It's not your imagination: over time hard drives accumulate all kinds of things that slow things down. PC optimization software can't solve obsolescence – if your computer is struggling to meet the system requirements for your OS or apps that's a job for more RAM or the addition of an SSD – but if the slowdown is software-related, it can really help.

It's worth noting that you can do much of what these PC optimization apps do yourself using Windows' built-in system maintenance tools, but that's time consuming; what's really being sold here is convenience.

1. Iolo System Mechanic

Enjoy a faster, cleaner PC with the best free PC optimization tool around

Iolo System Mechanic removes junk files and unwanted apps, blocks bloatware and unwanted auto-run settings, clears out RAM and wipes various logs, browser histories and caches.

Not only does this free up key system resources, it also eliminates traces of your browsing activity to protect your privacy.

Its PC optimization toolkit really does make a difference; whenever we've tested System Mechanic we've found a significant speed improvement, especially at startup. The free edition is excellent, but the two premium versions – System Mechanic and System Mechanic Pro – are well worth considering if you find yourself using it regularly – and Iolo is offering a 70% discount with the voucher code TECHRADAR.

The genuine performance boost we saw after running System Mechanic made it our favorite system optimization tool. Read on for four more of the best apps around for speeding up your Windows PC.

2. IObit Advanced SystemCare

A hands-off approach to optimization that's ideal for novice users

IObit Advanced SystemCare comes in two forms: a free edition version that covers basic house cleaning, and a Pro version that adds internet speed-boosting, real-time optimization, privacy protection, deep registry cleaning and 24/7 technical support. That's US$20 (about £15, AU$25) for a year, and the license covers three PCs.

Whichever edition you choose, IObit Advanced SystemCare's interface is well designed, easy to use and unlikely to frighten even the newest PC user. We'd deduct points for an installer that wants to add additional programs - that's hardly in keeping with the philosophy of keeping unwanted stuff off your computer - but they're easy to avoid if you choose a custom installation.

Like most of the free PC optimization software here, it cleans up files and folders you don't need, neatens up the Windows registry and corrects errors on your hard drive – all via a simple, slick dashboard.

3. Piriform CCleaner

Eliminate unnecessary files, clean the registry and manage programs

Piriform CCleaner has been around for a long time, and part of the reason for its ongoing popularity is that it cleans the parts of your PC that many other free system optimization tools don't.

There's a paid-for version of the optimization toolkit that adds real time protection and cleanup scheduling, but the free edition of CCleaner covers the important stuff such as removing temporary files, getting rid of browser caches, removing unwanted cookies while keeping the useful ones and so on.

If your PC just feels sluggish then this is the app to try first. It doesn't have all the advanced features of apps like System Mechanic, but the stuff it does clear is famous for slowing down PCs.

4. Ashampoo WinOptimizer 2018

A fast, thorough scanner plus a suite of well designed maintenance tools

Ashampoo WinOptimizer 2018's biggest selling point is its flexibility – you can scan for junk files, broken registry entries and browser cookies with a single click, and erase them all with one more.

Alternatively, you can dive deeper by selecting the 'Details' button to review the results of your scan one by one. Unlike some PC optimization tools, Ashampoo WinOptimizer gives you a full description of each issue it's identified, explaining exactly what it is, and why you should consider removing it. You can then make an informed decision about whether to erase or keep it.

WinOptimizer also includes a suite of 'modules' for routine maintenance tasks like defragging hard drives and optimizing startup processes. These are all tasks that could be accomplished within Windows itself, but having them all in one location is much more convenient than trawling through menus.

(In case you're wondering, Ashampoo takes its name from this optimization software, which cleans your PC 'like a shampoo'.)

5. Razer Cortex: Game Booster

Designed to help gamers wring extra performance from their PCs

If your system struggles when you're trying to get your game on, Razer Cortex: Game Booster could well be the answer. This free PC optimization software suspends unnecessary system processes, clears out memory and defrags your system to get the very best game performance possible.

Razer Cortex: Game Booster is available for Windows 7, 8 and 10, and while the differences won't make you jump up and down in astonishment - for most people the results will mean slightly smoother visuals rather than astonishing performance improvements - it does automate the fiddly process of turning off unnecessary software and services when it's time to play.

• The best gaming PCs for silky-smooth gameplay

We’ve said it again and again: Registry cleaners don’t speed up your PC. At best, they’re a waste of time — and often money. At worst, they can cause problems by removing registry entries they shouldn’t.

We recently covered why PC cleaning software was a scam, noting that a big part of the cleaning process — the registry cleaning — wouldn’t help speed up your PC. We’ll now look at what that is.

Registry Cleaners Demystified

RELATED:PC Cleaning Apps are a Scam: Here’s Why (and How to Speed Up Your PC)

Registry cleaners aren’t a magic button you can click to speed up your PC, as scammy PC-cleaning software developers would like you to believe.

The Windows registry is a huge database of settings — both for Windows itself and for programs you install. For example, if you install a program, there’s a good chance that program would save its settings to the registry. Windows would also save pointers to that program. For example, if the program were registered as the default program for a certain file type, Windows would save a registry entry so it can remember that’s the default program.

If you uninstalled the program, there’s a good chance it would leave all its registry entries behind. They’d stay in your registry until you reinstalled Windows, refreshed your PC, “cleaned” them with a registry cleaner, or deleted them manually.

All a registry cleaner does is scan your registry for entries that appear outdated and remove them. Registry cleaner companies want you to believe that this would result in big performance improvements so you’ll buy their software.

The Promises

Here are some promises that registry cleaner tools often make:

• Registry cleaners fix “registry errors” that can cause system crashes and even blue-screens.
• Your registry is full of junk that is “clogging” it and slowing down your PC.
• Registry cleaners also eliminate “corrupted” and “damaged” entries.

The following passage from Uniblue’s Registry Booster product page is a good example of the typical promises you’ll see:

“Have you noticed that the longer you have your computer, the slower it runs and the more it crashes? Often this is because whenever you install or uninstall software, adjust hardware or change settings, the Windows registry is updated. Over time the registry starts losing shape, accumulating obsolete, corrupt and harmful files. Left unchecked, your system can become increasingly unstable, run more slowly and crash more frequently.” [Source]

Wise Registry Cleaner, which is thankfully at least free, says it can also “get your PC running… more safely.”

If your Windows PC is crashing or blue-screening, you shouldn’t worry about “registry errors.” “Corrupted” and “damaged” registry entries also aren’t wreaking havoc on your computer, despite what the snake oil peddlers might want you to believe.

If your registry is indeed corrupted, you have bigger problems and a registry cleaner isn’t going to fix it — you’d need to use System Restore, at least. There’s nothing “unsafe” about not using a registry cleaner. The leftover registry entries that accumulate naturally aren’t harmful.

The Reality

In reality, registry entries aren’t a drag on your computer’s performance. The registry is a massive database containing hundreds of thousands of entries and individual registry entries are fairly tiny. Even removing a few thousand entries won’t make an appreciable dent in the size of your registry.

Now, if our computers only had a tiny amount of memory or an extremely slow hard disk, there could be some value to shrinking the registry a bit. But this will be completely unnoticeable on computers in use today. We don’t live in the days of Windows 95 anymore. The Windows registry has also become more robust as Windows itself evolved from Windows 95 to Windows 7 and 8.

Windows just isn’t getting confused and slowing down because you have a folder (known as a “key” in registry parlance) dedicated to an uninstalled program in your registry. It also isn’t getting confused because certain entries point to an outdated program.

RELATED:Why Using a Registry Cleaner Won’t Speed Up Your PC or Fix Crashes

No legitimate benchmarks showing a performance increase as a result of a registry cleaner have ever been released. If a registry cleaner offered boosted performance, we would have some benchmarks by now. It’s anecdotal evidence, but the majority of our readers didn’t find that registry cleaners helped improve their performance on modern computers, either.

In Some Rare Cases…

Now, it’s theoretically possible that a registry cleaner could help in some rare cases. For example, if a program left behind an invalid context menu entry in your registry, it’s possible that your context menu would take noticeably longer to appear in Windows Explorer when you right-clicked on something. It’s also possible that a registry cleaner would notice and remove this entry for you, solving the problem.

In another case, you might have a ten-year-old computer with a very small amount of RAM and a Windows installation that’s seen thousands of programs installed and uninstalled over the case of a decade. A registry cleaner might theoretically help shrink the size of the registry enough to make the computer perform faster.

Such situations are bound to be extremely rare. There’s no point in running a registry cleaner constantly — many registry cleaner companies recommend running their cleaner once a week. Such problems would be better dealt with by solving them when you encounter them. It’s likely that the average registry cleaner would cause many more problems than it fixes if it were run on a regular basis. And even if it’s completely harmless, it’s a waste of your time.

So If a Registry Cleaner Won’t Speed Things Up, What Will?

We’ve already covered why PCs slow down over time and shown you how to prevent this from happening. Rather than run a registry cleaner, you should just be careful about what you install in the first place. Even if you need to uninstall something later, a few registry entries — or even a lot of registry entries — won’t cause a slow down. If your computer is hideously slow or crashing frequently, you likely have more problems than a full registry and you’re probably better off reinstalling Windows or refreshing your PC.

We didn’t dwell on this part too much, but registry cleaners can also cause damage. There are so many different registry entries that could be present from so many different software programs that the average registry cleaner put together by a less-than-reputable software company can’t possibly account for them all. If a registry cleaner tried to be too aggressive so it could clean up as many “errors” as possible, it could easily remove errors that were necessary for an installed program, causing problems.

In summary, forget about registry cleaners and get on with your life. As long as you take basic care of your Windows computer, you don’t have to worry about your registry.