One approach we started with was to look at external dependencies and reduce the depth of the crate dependency tree.
Past improvements like removing redundant feature flags from diesel resulted in a significant improvement in compile time. Overall, we are looking to improve the developer experience through faster compilation for local setups.
We at Hyperswitch (an open source payments switch) have just issued our first RFC to improve our compile time and improve compilation performance with low resource machines.
From your experience, what are some of the approaches that you would consider effective?