I'm going to need to decide soon when to re-gild from Forest Seer to Atlas. Conventional wisdom states that happens when you can instant-kill until Masked Samurai is 2500 (so, about 2450 for Forest Seer). The optimal level is also the level that you stop instant-killing at (approximately). The thing is, according to my calculator, my optimal level is beyond a point at which I can be taking 5-10 seconds to kill a boss (depending on my luck with chests), which clearly isn't insta-killing at that point. On the other hand, I'm still moving pretty fast at those points. So my question is, about how much time can I take to kill a boss with it still qualifying as "insta-killing"?

Note: I know that I have a substantial way to go, as I'm getting somewhere around 2100 with Forest Seer while still insta-killing, so asking for my build and then saying "you shouldn't be switching yet." is not what I'm asking for. I know I shouldn't be switching just yet.