Weird that there isn't a topic about this yet, but I'm experiencing quite insane lag on both the EU and US servers. (Located EU)
My connection dropped from 4 to 3/2 bars on both servers. Besides that I fly all over the place while walking (Great with bushes next to you!), everything seems out of sync.
Also the 'Start' button takes 3 seconds to work, loading inbox, event hub, arsenal, whatever takes years.
After a single T3 level my whole party went up because of too insane lag..
I guess this has some relation with the new achievement, everyone plays Lockdown now.
Well, I just posted a relevant topic (10 minutes before you) and I have the same problem. Everything would be less awful if I hadn't bought my elevator pass yesterday. If this lag keeps on going for 2 weeks (the time this steam achievement works), then I won't be able to use my elevator pass at all.... This is so frustrating. And I doubt noob army of achievement seekers will stop coming soon.