Sorry, my initial comment probably come off quite differently. It's not that "using web UI" is the reason why this game has awful performance, that's more like a bellwether for the studio's priorities.
It's absolutely not the most important, or even in the top 10 most important problems here, but it shows really illustratively how much they care about making a game which performs in an acceptable way. (which is: not that much)
Also, it's not even one or two high-poly models dragging the performance down, what I was aiming at is that the game suffers from death by a thousand cuts - the LoDs are only a part of the issue, almost every part of the game is done in a sub-optimal way. So while the UI is not a significant part of the frame time, if they fix the most glaring performance issues, they will find that there won't be a silver bullet, the game is just a pile of small performance problems all the way down.
