https://www.youtube.com/watch?v=JqWvJK1uFn8
1 Destroy your VFS as soon as possible
2 How many times your VFX appears simultaneously
3 Amount of Triangles per VFX
4 Reduce the amount of materials , reduce the draw calls
5 Use Sprite Sheets / Texture Atlas
6 Make sure your Sprite Sheets are not above 4096X4096
7 The Renderer Settings of the Particle Systems should be equal
8 Your VFX is ready for batching
9 Some modules will cancel Automatic Culling
10 Avoid using "Application Framerate = -1"