This isn't really a bug, but the late game can still be rather laggy. I thought I'd try and help by sending a late game rather laggy file incase more files might still help.
A annoying part of the lag is when dupes stand around for 10 seconds so before they are assigned their next job which is just 1-2 tiles away.
Just Open the file. As time goes on this slow down dramatically. Dupes eventually stop and wait for nearly 10 seconds before they get assigned jobs.