Optimization is a job in and of itself for achieving high levels of performance from your graphic intensive game. Combinations of the above techniques can help you gain significant ground. Using these tools in the base- or Pro-level versions of Unity will allow you to dive deeper and make further adjustments.
Using Simple Colliders Instead of Mesh Colliders for Complex Models в Unity* Optimization Guide for x86 Android*
It’s important to use a combination of primitive colliders for complex objects that can be collided with instead of just throwing mesh colliders on everything.