I am starting to feel like the default vancouver area [like seattle] is very poorly modelled in terms of performance.
It's not "poorly modeled", and there isn't anything "wrong" with the area.
Just like Seattle, and New York area, they present quite a bit of custom scenery objects. In JFK, there are hundreds of custom buildings to represent Manhattan, and Vancouver in FSX has quite a bit of custom objects in the ports, downtown, etc. Same with seattle.
Of coarse, you can always turn this down with the "scenery complexity" slider, but you may sacrifice losing objects in your custom scenery add-ons.