Stat recalculations are pretty much immediate, yes. The only thing that takes a while is calculating the nodes with the most potential gains, since you're in effect calculating reachability, combined stat increases, etc, which is a few thousands to millions of calculations depending on how far you look.
FPS drops in PoE would not be caused by damage recalc: this is done entirely server side and on application of the damage/dot tick. That drop you're seeing is just loading the assets and recompiling some shaders, if anything.
But also: it doesn't need to be realtime. Your damage is a simple math formula, applied against another for enemy defense, for each hit instance. There are definitely some builds that stress servers due to the sheer amount of hits/tick, but that's a matter of optimisation. PoE lowers server ticks when it can't follow.
The post is talking about optimizing for build damage/resistance/etc, crafting a build. Which probably doesn't even take into account conversion shenanigans, over time things like wardloop that requires setup, cwdt and a load of other things. This is not an optimizable thing in any reasonable time, and human application of logic is pretty much faster.
FPS drops in PoE would not be caused by damage recalc: this is done entirely server side and on application of the damage/dot tick. That drop you're seeing is just loading the assets and recompiling some shaders, if anything.
But also: it doesn't need to be realtime. Your damage is a simple math formula, applied against another for enemy defense, for each hit instance. There are definitely some builds that stress servers due to the sheer amount of hits/tick, but that's a matter of optimisation. PoE lowers server ticks when it can't follow.
The post is talking about optimizing for build damage/resistance/etc, crafting a build. Which probably doesn't even take into account conversion shenanigans, over time things like wardloop that requires setup, cwdt and a load of other things. This is not an optimizable thing in any reasonable time, and human application of logic is pretty much faster.