We played the Witcher a few weeks ago, both with 2 and 4 players. Funnily enough the 4 person game went relatively fast, because one player was not afraid to take risks and rush monsters, rather than collecting more cards, trails, monster weaknesses and exploring etc. It still took a while because it was the first game, but I also got the sense that the game can be very fast, if at least one of your players is willing to take risks and forces the others to move faster.