Standard GTA V assets are heavy. Community-made "Citizens" can replace textures with lower-resolution versions.

Ensure your operating system isn't holding your hardware back.

Maintenance and system focus ensure FiveM gets all your PC's resources.

Turn off "Soft Shadows" and set "Shadow Quality" to Normal.

Regularly delete everything inside the FiveM Application Data > data folder (except the game-storage folder).

Lower to 720p (1280x720) or use a 4:3 stretched resolution.