Computers tend to slow down as time passes. Though it's usually not because your hardware is aging. Most hardware does not slow down with age. A CPU bought 10 years ago should continue to run like new today. The reason your computer gets slower is that you have software problems. Here is how you can deal with the issue.
You can speed up Windows 10, Windows 8, Windows 7, Mac OS, and Linux systems following these general tips.
Disable startup processes
When installing software, they sometimes, without your permission, start up whenever you turn on your computer. Spotify, Discord, Amazon Photos, Adobe CC, and much other software are culprits. The more software you install, the more you possibly end up with startup software. The more startup software there is, the longer it takes for your computer to start working when turning it on. This gives the illusion that you need to warm up your computer when it fact it is just the clutter taking up time. To make it worse, the bulky software running in the background slows down the general use of your device too. You'll want to disable any software you don't need right away. I prefer to manually start software if I need it. The trade of waiting two seconds to boot the software is much better than the computer slow down in my opinion. Especially when you don't need everything at once.
To disable startup processes on Windows, press ctrl + shift + esc to open the task manager. Navigate to the startup tab. Select a single process you don't want to start on boot then click the "disable" button at the bottom right of the task manager. Do this for all processes you don't want on startup. Do not disable system processes such as "Realtek HD Audio...". Disabling processes does not make the software unusable. It only means that it won't start up the second you turn on your computer.
Close software when you're done
More running software means you have less CPU/GPU/RAM resources available. As mentioned above, the more software there is running, the slower your computer gets. To make sure you have plenty of resources available for the software you need, closeout whatever you don't need. This especially counts for the RAM hogging Google Chrome tabs.
Disable disk hogging operations
Some cloud syncing software like OneDrive and the Google Drive app scan your entire backup location for files. When you have thousands of files, this easily clogs up your disk utilization. The situation can even be worse when you have an anti-virus starting a detailed scan. An anti-virus' detailed scan may scan your entire computer's file system. Which could be many thousands of files... It isn't exactly hardware resource cheap to scan the file system, so you can expect your hard drive to be taxed hard, thus your computer gets slower. You can notice the effect when editing videos or watching HD videos on YouTube. This is most problematic on outdated storage devices like hard disk drives(HDD). If you have a modern solid-state drive(SSD), the effect may not be so bothersome. If you need your computer to be faster, cancel your anti-virus' detailed scan or pause cloud syncing on software like OneDrive.
Upgrade your hardware
If the tips above aren't working, then you might have a more serious problem at hand... Hard disk drives age or maybe software is getting too resource expensive for your hardware. You might need to upgrade some of your computer's parts.
You can easily check what should be upgraded by looking at the task manager. Check out the performance tab. If you're experiencing slow down, check out what piece of hardware is being taxed. A higher percentage means the hardware is working harder.
If your disk usage is high: In 2020, you definitely should look into getting an SSD if you're running on the old school mechanical HDDs. Nearly every SSD is several times faster than the common HDD. Getting a fast storage device could mean your computer boots up faster, files scan faster, and other general software like games load up faster.
If your GPU is high: For gaming, upgrading your GPU usually makes the biggest impact.
If your CPU is high: For other less intense software, a CPU upgrade usually makes a bigger impact. A great budget option for Intel processors is the 9th gen Intel i5.
Before buying parts, be sure that your computer supports the upgrade! Not all hardware is universal. Laptops and desktops for example are completely different form factors.
Factory reset your computer
If even a parts upgrade does not help, you might have a virus or some other form of malware. Something may be trying to farm money through crypto currency mining by maxing out your hardware resources. If you have installed shady software from unofficial websites, you should be extremely cautious. Anti-viruses are not 100% reliable and don't catch everything. If you suspect something dangerously unusual, factory reset your computer.
The non-mechanical computer parts do not slow down with age. They eventually fail, but not slow. Mechanical parts like an HDD can slow down, so avoid them and go for anan SSD. A computer should run just as fast as when it was bought brand new. The load of additional software is what slows it down.