A well configured computer consumes less electric energy and provides a much more pleasant user experience. So, we are going to give you several steps for this task that in our opinion can be done by anybody without technical expertise. They are principally based on software because if the problem is caused by those pieces lying on the PCB like chips, capacitors, resistances or others, you are not lucky!
Each operating system is different, but the principles are the same. It only requires the understanding about which are the main causes of slowness.
Check startup applications
When the system is not capable of using the processor or memory in some circumstances, it starts to slow down even completely without the possibility of doing nothing, but waiting.
Some very intensive software is capable of using all resources, although most of the time the issue appears from the mix of numerous applications running in background processes. That happens usually in Android!
In Windows you can check how many applications are running at startup thanks to a tool called "msconfig" (Start > Run > msconfig) or if you prefer a more advanced one we suggest downloading a very handy software from SysInternals called "autoruns".
Linux or Mac must have similar methods for configuring startup applications, and you can expect a really increased performance after this step. The advice is to uncheck all inherent software and seeing what happens. After, you can reactivate them without problems so there's not too much potential trouble here.
Disable unnecessary services
In the last years a new concept of background process has arrived with the name of "service". A service is another application running in background and then consuming available resources.
In fact, several services will never be used in the lifetime of the computer, but some companies want to avoid customer problems so they decided to leave all the lights of the house turned on in case somebody enters a specific room. That's a high price to pay in terms of electricity consumption and for that the guiltiness, but they are not alone on it since they can be turned off.
If you think on the subject, you could easily imagine an operating system that asks users what kind of lights need there and those that not. Also, you could create an assistant for turning them just in the necessary moment. But the engineering protocols are very, very irrational because it's easy to identify for instance GPS applications in background without the GPS (that is hardware) activated. Same for Wi-fi, Internet or dozens of functions. This is critical for the energy bill and its consequences to the ecosystem as electricity today means contamination.
There are intensive lists about what kind of services can be securely disconnected, but this operation should be made with care because a wrong move implies considerable issues.
Hard drive defragmentation
Normally this step doesn't mean too much, but there are situations in which could be important. Fragmented means that for instance an archive lies in different parts of the hard drive in a non consecutive manner, so the hard drive needs to take extra time for reading all little pieces. It's recommendable to do it if you are constantly copying, moving or erasing.
The last resource: operating system reinstall!
It's usually the most effective method, but it's time consuming and there's always the risk of losing data. In our experience with care and the help of an external USB drive you should not lose more than an afternoon. It's really easy; first backup all data, after introduce the original CD or DVD, reboot system and finally read and follow the instructions that appear in the screen. The only possible setback is when the optical drive is not configured for autorun, but that's rare nowadays.