As your TypeScript project grows, you might notice slower build times, especially with large or complex types. To diagnose this, you can use `tsc --diagnostics` to profile the build and see where time is being spent. Deeply nested types or complex generics can slow down the type-checking process, so simplifying your type definitions can help. You can also optimize your build by using `skipLibCheck` in your `tsconfig.json` to skip type-checking external libraries. For large projects, consider using `tsc --build` mode, which allows incremental builds to avoid recompiling the entire project every time. By profiling and optimizing your TypeScript setup, you can speed up build times and improve development productivity.