I think you can tell people other ways that you degraded their experience intentionally. I guess I’m actually fine with popups too. The goal is to make Chrome known as the slow browser so people stop using it.
I think the "Stop SOPA" banners are a good model. I think people are already suspicious of Google, I don't think they'd need all that much convincing to try switching to Firefox. After a week, at least half will have switched back, but that's just how it goes.
And if you degrade their service, they won't blame Chrome, they'll blame you.