Just added the fake draw step (the background image loading and pushing textures one by one was already implemented). Not sure if it's done 100% correctly, I simply binded the texture and drawed a triangle very, very far away from the camera (is it a problem if its outside the view frustum?).
It's still noticable when a texture gets loaded, though its more equal spread all over now. It may also be the hardware though, I get the feeling that this laptop is going to a digital heaven soon... My desktop loads the entire thing way faster, even though that videocard is slowly starting to date as well. Not only the loading goes slow, the entire game runs slow so its add up.
This would bring me to the conclusion that, like Spiro said, truly "smooth" streaming isn't possible. Then again on a more modern card it would most likely be less of a pain.
I still wonder though, old games like GTA on a PS2 did the same thing (I think). Of course those textures were really low-res, but so was that hardware 10 years ago. Though you could clearly see the scene getting loaded step by step when traveling too fast sometimes, it didn't noticably hurt the performance. And more recent games such as GTA IV are doing it with more (and more detailed) textures on "dating" hardware such as the XBox or PS3. Are they doing something really different, am I just fooled by low-res textures, or is their whole memory architecture different anyway? Just curious.