Eli5 why do computers get slower over times even if properly maintained?



I’m talking defrag, registry cleaning, browser cache etc. so the pc isn’t cluttered with junk from the last years. Is this just physical, electric wear and tear? Is there something that can be done to prevent or reverse this?

In: Technology

Registry cleaning and other stuff doesn’t solve all problems completely. Some errors still remain, some junk still accumulates, more software is installed/updated over time and this new software is often “heavier” and slower-working than older versions. If you format a drive and do a clean reinstall of the system with (optionally) only the old versions of the software it had at the start, it should work faster again.

It’s not really really getting slower, it’s mostly the fact that new software is developed for never faster computers, so they will run slower on older computers, and as apps get updates over time, they will run slower and slower

As an analogy if your computer is a car and the road is the software, it’s not your car getting less powerful, it’s the road getting steeper

Newer versions of software is written for newer faster hardware, so sometimes it asks to do a lot more stuff at once, which can be taxing on older systems. Unfortunately, there’s not a lot you can do about that other than trying to tell it to stop running so many background. So even if your computer hasn’t physically degraded at all, it’s slower than it used to be.

PC’s can slow down only a few ways.

1. Electronic failure. Parts can break, but on a PC most components that break will prevent it from working at all. The exception is a hard drive or a fan, which are the only two parts that can slow down over time.

2. Hard drives. Hard drives can slow down as they fill up, get erased, and rewritten. Your computer knows where files are, but imagine reading a book where each word is on a different page in random order. You have to flip back and forth to read it. This problem with hard drives can be fixed with a format and reinstall. A drive known as a “SSD” can also help prevent this from happening as much.

3. Heat. With the death of fans, your computer can overheat. Your computer tries to prevent this by using less electricity, and running slower. This can be fixed by cleaning, or replacing broken fans. Sometimes other measures like new paste under the cpu cooler can be required.

4. Software. Software can be added and added, slowing down your computer just like the car weight analogy. Sometimes removing the program leaves behind traces which still slow down computers. Most techies call this “bloat” or “bloatware.” A format and reinstall can fix this. This is the most common way PC’s “slow down” over time.

Edit: it’s important to note that generally PC components like processors and ram never slow down. It just seems like it over time because of other factors. A good clean, a new SSD, and your PC will run just as good as new, at least for the vast majority of cases.

They don’t, they run at the same speed throughout their operational lifetime. You’re just making them do more that they weren’t doing before.

As an IT professional, programmer and system admin please:

– Stop defragging. It does basically nothing nowadays, certainly nothing worth the disk wear or the time it takes. Defragging is a handover from the days of 20Mb hard drives on older filesystems on slow-latency hard drives. Just stop it. Especially if you have an SSD – you’re literally just wearing the SSD away, for no reason. If you want to avoid the need to defrag, don’t run your hard drives more than 90% full, that’s when things start to fragment to jam them into the gaps. If your drive isn’t more than 90% full, it’ll sort itself out and likely will never fragment in the first place. And modern PCs will basically not noticeably slow (even on a benchmark measurement) just because they’re slightly fragmented.

– Registry cleaning – again, does nothing. The registry on an average machine is maybe 50Mb-100Mb or so? Pathetic by modern standards. Cleaning it does nothing. You can remove services and auto-start entries, but use a proper tool for that, not some pay-for junk off the internet, or in the registry itself because if you cock it up, your computer won’t boot properly. Sysinternals has Autoruns available to you for free, but pretty much most of what it does you can do with Windows 10 task manager, etc. on its own.

– Browser cache – again, does nothing. You’re just making the problem worse. Modern browsers manage their own cache and clearing it out makes nothing faster, just the opposite. Unless the page you are loading is not the page you expected (i.e. it’s not up-to-date), cleaning your browser cache is entirely the wrong thing to do.

What you want to do:

– Make the computer do less. Have less programs installed (no, it doesn’t matter how full your disk is, it’s to do with how much stuff is running all the time). Get rid of anything you don’t need to be running 24/7 (e.g. get it off your taskbar, stop it running with Windows, or stop it staying around all the time – it’ll still work when you actually need to use it). Steam, for example, does not need to be in your taskbar 24/7. Stop it, using the options in the program or Autoruns. Then when you want to play a game, you run Steam.

Personally, about 4-5 taskbar icons (by the clock) I find annoying. I work to get rid of them. Almost all of them can go. The Intel display one (unless you think you need to use it), nVidia icon, Java, Steam, printer monitors, etc. etc. Get rid of them. The screen will still work, your games will still work, your printer will still work. But you’re not constantly running them 24/7. There are also dozens of services, programs that run on startup, and other junk that’s always running that don’t need to be. Almost all third-party program services (e.g. game launcher services) can be changed to manual startup (and then they will start if they’re needed, but won’t if they are not). Uninstall stuff you don’t use.

Your machine is no slower than the day you bought it. It’s just running all the shit you installed on it for the last few years and never removed and which is running 24/7 even though you don’t realise or don’t even use it any more.

Check your task manager and see are any programs hogging cpu, memory and disk.

Check the temperature of the hard drive, SMART data and temperature of the onboard components. If it is a laptop and things are hot swap out it’s thermal paste and clean it.

Another good one nobody seems to have mentioned. Dust. Give your old pc a good Hoover out occasionally. Make sure it has good air flow, clean the fan and the filters if it has them.

5400 rpm hard drives. Companies love to install them in inexpensive computers. If it doesn’t have an SSD, don’t bother. Win10 updates on a spinning disk is the “death” of a computer.

It’s a combination of factors:

More tasks / software bloating – The strongest of these is that normally you are asking your computer to do more tasks than before – some of this is subtle stuff brought in with Windows Updates and especially Chrome updates. Chrome started nice and efficient and a hell of a lot faster than Internet Explorer but has slowly gotten fatter and fatter. But it’s not solely the browser’s fault. As PC Processing Power, PC Memory, Browser Stability and internet speeds have all generally increased so websites have gotten more and more resource intensive (especially with the copious amounts of various advertising they force on you). The same holds true for a lot of software out there – that as PCs become more powerful so the software changes to leverage more of that power.

Security, security, security – A HUUUGE part of OS, browser and software updates is security based. It’s very, very seldom that security updates result in increased speed or performance.

Failure Rates – RAM, CPUs, GPUs, HDDs, SSDs all have failure rates and these tend to get worse over time especially if there’s significant heat in your system. I not talking total failure I’m talking bad sectors, I’m talking memory parity errors. Modern day OS and firmware do an immensely good job at handling this invisibly. Often you may not be aware that you have bad sectors at all. The sector has been discretely marked off limits and a replacement sector has been allocated. But when that happens it’s basically introducing a permanent fragmentation onto your drive.

OS / Registry scarring – Back in the good of days of Windows 98 it was a pretty regular thing to reformat your system at least once a year – sometimes due to a complete OS crash – but often wanting to have a clean version on because over time you add and remove programs, you get the occasional virus, you run registry cleaners and you install a ton of updates and well as any tinkering you may have done yourself in the registry. This all leads to the registry and system files not functioning as well as it should. Registry cleaners are a mixed bag – they spot a lot of problems but their solution is to delete the problems.

Top Recommendations:

Antivirus – check that you only have one anti-virus on your system and that’s it’s not McAfee. Multiple antivirus apps will interfere with each other. These days Windows Security is an excellent choice for your antivirus needs.

Switch to an SSD – If you haven’t switched yet and you can afford it I would highly recommend it. It’s faster and doesn’t suffer from fragmentation (assuming you don’t live with your system drive 99.95% full). HDDs are still good for storage drives by your system and games should be running off an SSD.

Clean install – Especially if you’ve upgraded between windows versions or even between major builds you will be surprised how much better your PC will run on a fresh system. This goes well with upgrading to an SSD. Download the USB installer from Microsoft’s website and get a completely fresh version of Windows with no manufacturer bloatware on it. Do make sure tht you’ve backed up EVERYTHING you need: files, passwords, websites.

Remove software that you’re not using – especially any software that installs it’s own services. I try where possible to use portable versions of applications – that way you know that they’re not cluttering up your registry, system files and services. Also always check if there isn’t a windows app that does what you want already.

Hosts file – Use your hosts file to block advertising sites – this is fairly technical and I don’t recommend for the average user but it’s preferable to using ad blocker software. It’s a fast, nasty but uncomplicated firewall essentially. What I do when I find a website that’s running slow it I analyze that particular website on [webpagetest.org](https://webpagetest.org) – I identify the external links which are causing delays and block those via my hosts file.

Upgrade you memory – definitely these days if someone has only 4gigs my instant recommendation is upgrade, upgrade, upgrade. Running Windows 10 you want 8gigs minimum.


The only real answer is that your computer does not get slower. It can’t. Aside from some actual hardware problem. It’s just becoming less capable. It’s the equivalent of thinking a pocket calculator would become slower over time.

Follow up question. Who on earth is still using a computer with a HDD? I just bought a 1TB Samsung SSD on Amazon for $109. You can get a 250GB for $30 tomorrow. More than enough to run your OS and frequently used programs.

Also. All third party Anti-Virus software is worthless for a single user home PC. Worthless. They just steal CPU crunch time and RAM with zero ROI. Windows defender is enough.


Take a look at [Bill and Andy’s Law](https://en.m.wikipedia.org/wiki/Andy_and_Bill%27s_law#:~:text=Andy%20and%20Bill's%20law%20is,that%20new%20hardware%20can%20provide.)

Basically, software gets more complex over time to take advantage of new hardware. If you don’t upgrade the hardware, the new software will just take longer to run.