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Myths: Does Deleting the Cache Actually Speed Up Your PC?

Every time you ask somebody with a reasonable level of tech skills what you should do to speed up your PC, they start jabbering on about running ccleaner and clearing the cache. But does the act of clearing a cache really speed things up? Nope.

Most people assume that all temporary files are just clutter created by lousy applications, but that isn’t actually the truth. Cache files are created by apps to store commonly used information so it doesn’t have to be generated or downloaded again.

It all comes down to latency.

If it takes 2 seconds to access a small image file from a web server, that might be fine once in a while. But modern pages are made up of tons of little images, style sheets, and JavaScript files, most of which don’t change every day. Multiply those by all the sites you visit multiple times, and you are talking about a lot of time wasted, not to mention bandwidth.

If your browser doesn’t have the full CSS immediately, it can’t start rendering the page, leading to more delays. That’s why the second time you visit a page on the same site, it displays the layout of the page very quickly. It has been cached.

The problem can get even worse when an application needs to generate a set of info that might take a while to regenerate every time the app starts up again. Instead of doing all that initialization every time, it does it once and caches in a file.

When you wipe the cache, what you are actually doing is starting all of that work over again, and slowing your computer down in the process.

Exceptions to the Rule

If your computer doesn’t have a ton of drive space, and your applications have created way too many temporary files, you might have a real reason to clear out the cache, or at least reconfigure your apps to use less temporary space.

This was even more true in the days of mechanical spinning platters in your hard drive, where the latency for a hard drive to find each file would increase when there were zillions of little files to load. These days you should have a solid state drive in your computer if you are worried about performance, and random seek time isn’t a problem anymore.

Cache corruption
There are times when an application cache becomes corrupted, and requires a wipe to get things going again… Or perhaps the cache is just out of date and has old files — this is a big one for web browsers. This problem usually manifests itself as an issue rather than a slowdown though, so while you can fix problems this way, it isn’t the best choice for performance.

Lousy Autocomplete
Another reason people wipe the cache is a side effect of a badly written auto complete algorithm. Let’s say your application’s search box attempts to give you a dropdown of recent items… and the algorithm is slow and clunky. You would end up having better performance while searching to disable the history or wipe the cache, which leads people to believe that cache is bad, when the reality is that cache is good… Bad apps are bad.

The Real Reason You Might Want to Delete Some Cache

Deleting the cache is definitely something you’ll want to do if you are worried about your privacy. Just keep in mind that deleting the cache will only sorta delete those files — unless you overwrite the free space, you aren’t really deleting anything permanently. All you have to do is run a few utilities, and those deleted files are most likely going to be recovered.

Test it for Yourself
You don’t have to take my word for it, because it is easy enough to test for yourself. Set your browser to open a set of your favorite web pages at once, record the time it takes to open them. Then wipe the cache and load the same pages again.

So where does that leave us?
If you want to wipe the cache, there is no harm done. Your apps will dutifully rebuild their caches quickly, and things will be humming along faster than ever in no time at all. But now you will realize that clearing cache doesn’t usually improve performance.

Lowell Heddings, better known online as the How-To Geek, spends all his free time bringing you fresh geekery on a daily basis. You can follow him on if you'd like.

  • Published 08/2/13

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