Unlike GTA V, which uses a more arcadic physics system, GTA IV utilizes the Euphoria engine. This creates procedural animations for characters. If you shoot an enemy, they don't just play a pre-canned death animation; they react realistically based on where they were hit, trying to balance themselves before falling. This makes shootouts and car crashes feel incredibly dynamic.
If you have a 2GB RAM laptop, delete the audio files. Open your GTA IV directory > pc > audio > Delete sfx.rpf (Backup first!). The game will run 40% faster, but you will lose all sound effects (not recommended unless desperate). Gta Iv Pc Download Highly Compressed