If you could refactor the code into smaller and faster SQL, that means the code was badly written, not that SQL (and stored procedure language) itself is bad.
Also almost every algorithm can be written in PLSQL if needed, so yuu can surely improve on the O(n^4) time complexity.
I agree with the procedure change tracking, that's much harder, but server side programs can be extremely responsive (low latency) and powerful.
I was using it and PL/pgSQL together to modify data and although I had to think differently, working in the relational space even with modifying data is awsome (of course you have to use cursors).
Also almost every algorithm can be written in PLSQL if needed, so yuu can surely improve on the O(n^4) time complexity.
I agree with the procedure change tracking, that's much harder, but server side programs can be extremely responsive (low latency) and powerful.