That "Fast-Cool" Animation

Hey i know this sounds extremely confusing but on some of the websites here they have that really like slow-to-fast-or-somethin something… :h:

like this:
http://www.rodrigofcampos.com.br/

You know when that little logo goes up at first at the nice fps (or w\e) im totally not sure but if anyone knows how to do this can u reply back?