I don't know why people have trouble with Pandemonium. I don't think everyone does.
I had a little lag in Pandemonium, but not like I did in...all of Europolis. ...Also had a moment where Mira kind of glitched out. Wish I'd gotten a screen shot. If it happens again, I'll be ready. But yeah, I don't think Pandemonium is as big of an issue as Europolis in terms of lag (for most people), as far as I know.