Why GTA IV has a poor performance?

[TeddilaHD1999]

We all know GTA IV is problematic on PC thanks to its bad performance, even on newer rigs. I know some people recommend the console versions.
But the truth is, GTA IV runs even worse on Xbox 360 and PS3. I played the 360 version and, believe me, it dips below 20 FPS when I drive fast, there are lots of explosions happening and in some areas of Algonquin.

So why GTA IV has a very awful performance?
And the answer is very simple: its game engine, RAGE.

To begin with, the first time Rockstar used this engine was in a simple Table Tennis game. It only had some character models and some animations. The same version of the engine was used in GTA IV, but it wasn't ready to render a huge city with lots of pedestrians and vehicles roaming around. Thus, the game suffered.

Now look at the newer Rockstar games released: Red Dead Redemption, Max Payne 3 and GTA V (Not counting L.A. Noire because it doesn't use RAGE), they all run and look way better than IV on all platforms. Why? Because they mastered the engine. They may have completely rewritten it after they learnt from IV. Both MP3 and V ran excellent on PC on day one proving that all the performance problems related to RAGE were finally fixed.

Now here's a honest look on the port of IV. Ignoring the performance, Rockstar Toronto did a great job. Better textures and graphics, less Pop-ins improved multiplayer, Video Editor and a Custom Music Radio, this is what a PC port should be. They did their best.

All in all, we have to forgive Rockstar for the performance. It was their first use of RAGE on an ambitious game, and definitely the first time they used their engine on PC. With more powerful PCs, we can run the game decently as long as we don't max the sliders and the shadows. Those are CPU bound.

[60]

I have other people with same CPU and GPU as me, maxing out the sliders and shadows. Something is wrong.

[RGC]

You're right! :) But it doesn't mean that it makes the game to run worse,it just messes with it.Yeah,it even makes it go slower,but if I change the game's options,even on better,the game runs pretty good,I think even 60fps for like 1-2 minutes,and then again,it starts to go bad.But even if I change the brightness or something,it does it.So the game is messed up because of that,not that it's worse,it just made it a strange game.