I lived here for 14 years now, have no idea what traffic you re talking about..
Come up I-5 from Tacoma in the AM rush and try to get to Lynnwood in decent time (or the other direction in the PM).
Absolutely not. I wouldn't do that. Take Aurora through the city. At some point, depending on where you're going, you might want to find yourself on Greenwood, 15th, or Lake City, but don't even consider getting onto I5 until 145th.
Guerrilla filmmakers don't take I5. There, that's sort-of on-topic.