>>536642264
modern game engines are really really bad at handling having lots of animated enemies on screen at once
devs are encouraged via tooling to use cpu-based animation systems, which buckle quickly as you add packs to the screen
if you want GPU instanced animations, you have to use custom tooling and a lot of tricks to account for the lack of blending you can do with CPU based animations
thus most games with budgets sufficient to produce something that (You) would call "like in lost ark" choose to scale back the number of enemies on screen and make the ones on screen take longer to kill