FPS Drop

[Ms. Mudpie]

The city was made by an idiot who didnt include certain things to improve FPS

This is the main issue. The map is horribly unoptimised and the way it's laid out (large open spaces) leads to the Source engine having to render too much at once, even without all the things people are building. It's why bits of the city disappear and reappear when you enter it. 

All you can really do here is slow down when you take a corner so you don't crash into anything when the game locks up.