The aggravating thing about Perilla is that you won't even see it until about this time of year, and it all doesn't germinate at once. You will feel like you have it knocked out pretty good, but when you come back to the plot a week later the stuff is everywhere again.
At this time of year I want to get plots planted and/or do some final maintenance and get out, but that stuff won't let it happen. Like you said, it pops up quickly. And I might add that it can make next years seed crop quickly too.