How to optimize a PC game?

We are creating a forest like game in Unity for our Final year project. The scene has a large map with 1000+ trees which makes the scene very laggy. How do I improve the performance of the game without losing the quality? And many times the light and shadows seem flickery. How do I fix that? And what are some thing I have to keep in mind before creating a large scene?

Here are some general tips:

  • If you use colliders, make sure you use only 1 collider per tree. Capsule & sphere colliders perform the best.

  • Avoid mesh colliders.

  • Occlusion Culling could really help.

  • Try using as few materials as possible.

  • Lower the quality of the shadows, it’s hard to notice the shadow quality anyway.