If you are coming from another city, or have been playing for a while, it is recommended to clear your cache of corrupted files. 

If your menus are lagging, enable fix UI lag in the FiveM settings before you join the city.
 

If you're failing to load the game, you most likely have to raise your extended texture budget.
I recommend adjusting it around 50-85%, raising it if needed in dense areas. Too high or too low will lead to adverse effects such as falling through the ground and odd game behaviors. Whilst in this menu, disable V-Sync as it can lead to major FPS drops.

If your HUD / UI is bleeding off of your screen, you can adjust your safe-zone size.

General voice settings can be found here, such as enabling “push-to-talk.”