I picked up a codebase where people were optimising for performance throughout the development it's now very hard to change or refactor because there are preemp

I picked up a codebase where people were optimising for performance throughout the development it's now very hard to change or refactor because there are preemptive performance optimisations and caching everywhere (front and backend). It makes far more sense to create an extensible solution and then identify and fix the bottlenecks as the vision about the "final product" (or version x) becomes more clear.