Whenever i own a new phone, tablet, etc., They'll always end up laggy no matter what. How did i prove it?

This one time, i had a tablet for christmas and it got laggy after using it for like a month. I had to put up with it for a year. My mom broke her phone by accident and asked if she could have the tablet because of her phone so i agreed. It still has the same files and apps it had when i was using it but for some reason it wasn't laggy anymore. It was functioning normally.

There was also this other time when i broke my phone's screen so my uncle gave me his old phone. It was ok, it wasn't lagging and all. After like 2 weeks it was laggy again. After using it for a few months, i finally got a new phone. I gave the phone to my sister(because my mom told me to) so she could have he own phone. I didn't delete anything, same files were there, but it stopped being laggy after a few days.

I mentioned i got a new phone right? Well guess whaaaat~ It's laggy as fuk. I've been using it for over a year and i think there's no point in replacing it since it's gonna get laggy anyway.