Whaa Whaa Whaa GTAIV was a crappy port.
Seriously, give it a rest, it wasn't unoptimized, it wasn't a poor port, for what it was it ran extremely well. No other game, even to this day, has dozens of fully destructible vehicles and NPCs on screen constantly. Of course that is going to be CPU intensive. THAT IS WHY THEY GIVE YOU THE OPTION TO TURN THE NUMBER DOWN. That is also the reason that the settings used for consoles were basically low.
If all you idiots cared about was the ability to run it on max settings on your mid-range hardware, then the only thing Rockstar would have had to do to optimize the game would be to limit max settings. Make what they called medium the max, and you all would have been happy. The game would have run perfectly fine on mid-range hardware on "max" settings. And you all would have talked about how well "optimized" the game was. And it still would have looked way better than 720p Low settings we got on the consoles.
The fact of the matter is that when the PC version game out I played through it on a Athlon X2 4400+ and an HD4670, and it looked better than the console versions.