There is a discussion here: http://forums.vwvortex.com/showthread.php?9007849-2018-Transmission-Issue
Turbo lag has got nothing to do with this issue. Completely different thing.
I find it happens when you are needing to downshift 3+ gears at once. The TCU doesn't anticipate that kind of shift "at times" and you'll get that 1100ms shift. I say at times because it does occasionally work but not often. You're better off manually downshifting in those cases. Check the wiki on this Transmission. Will help better understand why it does this. https://en.wikipedia.org/wiki/Direct-shift_gearbox
Agree with this assessment - transmission program is not anticipating changing condition and does not read your mind and is slow to respond. I find with my 18 R DSG that I need to manually shift down if I want to go quick, not just stomp on the gas, as if I do, I get the delay noted by the OP in mine as well. It is something you can "drive" around, once you know what to expect. Should it be that way, probably not - but this is only a $40k car so there have to be some gives!