Hello,

-Your laptop could be slow because it can be affected by a "Virus".

You can use Adwcleaner to find some problems or virus on your laptop.

And CCleaner for delete temporary files, registry error etc...

-Your laptop can be slow because it can be dusty.

You can remove the bottom panel and clean your motherboard from any dust.

-> A laptop with lot of dust will be hot and will be slow.

-If you move with your laptop running you can provoc some damage to your hard drive.

-> Bad HDD is a cause of slowdown laptop

Several factors can cause slowdown on your laptop

:)