Easy method to fix my slow and old Computer or Laptop

I got used to the time my Computer needs to fullfill his tasks, but recendly it takes so much longer to start the computer, to start the E-Mail Programm and to surf different webpages.
Google could not help me out, the webpages I looked through descriped different topics and the tipps were not usefull at all. I then asked a friend of mine to help me out, because he does know a lot about Computers, he gave me a link to a software. I installed the software and it fixed the issues within seconds.

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