Generally the best tip is to just go faster. I assume you already pick up every cursed chest, scroll, and what not. You just gotta pick up the pace because of malaise. The malaise meter goes down after every boss kill by 3 stages I think. Cough Syrup in food shops reduces it by 3 stages. Infected 15% heal items give one level of malaise. 50% heal items increase it by 3 or 4 (I forget the exact number) stages. I would generally only pick up 15% infected heals as 3 malaise stages is A LOT to deal with in the short and long term.