Laptop starts very slowly?

When I start my laptop it takes more than 15 minutes to start up. What can I do?

https://www.pchelpsoft.com/pc-cleaner/de/?tracking=PH_DE_PP_GO_SE_PCC&keyword=laptop%20startet%20langsam&campaignID=ADWORDS

I'll put it this way, reinstall.

Otherwise local disk C: / click with the right mouse button at the bottom on properties and then clean up, everything that can be removed is displayed, it takes a while with 1 terra byte it can take longer. If that doesn't work, reinstall as I said.