Few fps despite 1070 ti and i7 8700k?

Despite a 1070ti, an i7 8700k and 32GB ram, I have little fps in Fortnite a few days ago I had 300 at a time only 50-70 and I haven't changed anything, in every other game like Gta 5 everything goes well with the usual fps and I don't know what to do next can someone help me?

Maybe update the drivers with GeForce Experience. If that doesn't work, reinstall Fortnite.