Dust can be a major factor when your laptop starts to slow down on you. Computer processors generate a lot of heat when in use, so to ensure they work at their best they must stay cool. When processors get to hot they start to slow themselves down as a means of not producing any more heat. In some cases, this can slow your computer down to a crawling speed.
Normally one fan and some heat conducting material is responsible for carrying the heat away from your processor. But, as you can see from the picture this can get blocked up over time making your processor heat up and slow down.
You can do a few things to avoid this build up like not using your laptop on any fabrics. Although over time this will happen regardless, here at the Tech Corner we clean up at least one laptop a week. The picture above is an example of another clean up completed and another happy customer to follow.