Technically speaking, computer hardware does not typically slow down over its life. Rather, there are several other reasons why smartphones, tablets, and PCs start to seem less snappy. Thankfully, you can take steps to improve your existing device's performance. Here's how:
1. Memory Bloat
Whenever your apps require an update, they become larger and tend to include more features. They may also receive significant redesigns, periodically. The extra functionality and glitz require your device to do more computation than it did when you first received it from the store.
Once your device doesn't magically speed up to compensate, it has less spare capacity available to respond quickly. New apps tend to take up much more space in your device's storage, causing it to slow down.
Your device only has a limited amount of fast 'Random Access Memory' (RAM) available. RAM is one of a device's data storage components that keeps our device fast and convenient. However, it is limited in capacity. So, when your device runs out of RAM space, it can make your device much slower. Consequently, data storage and flash memory take considerable time.
2. Excessive caching
To make apps run faster, some apps store copies of them in the RAM, that they think the user might want to see again to speed things up. For example, a web browser might retain a copy of what the content in each tab looks like at any given moment.
This is known as caching and it makes things work much faster until your system starts to run out of memory. For caching to be effective, the amount of space devoted to it must be carefully managed by the application and the device's operating system. There are some app developers who don't put the effort that they should into doing this well, causing their apps to slow down over time, and also drag the rest of the system down with them too.
3. More and more software
It's not uncommon for useful software to be accompanied by less than useful add-ons like browser toolbars, that use system resources and impact performance.
Additional software can slow a system down in many ways, filling up permanent storage, using up more RAM space, and using the computer's central processing unit 'in the background' without you realizing. Consequently, all these factors can cause your system to have fewer resources available to respond to you promptly. It may also be likely that some of the computing capabilities of your device are also being used by malware, through viruses, worms or other malicious software.
4. What can you do?
There is not much you can do to match the performance of what's new on the market, as newer devices generally have faster components. But with some effort, you can make the most out of your existing device. The best thing you can do is uninstall unnecessary apps and add-ons, uninstalling anything you may not need.
One other step you can take is that after carefully backing up all your data, perform the equivalent of a factory reset, reinstalling the operating system from scratch and adding the apps you actually need.