"they don't understand how to write efficient code"

Nothing new. Back around 1982 a so called "Business Case" for converting a major balanced line tape master file application to DB was fudged together by adding up the cost of all the sorts / merges and claiming they would go away with a Direct Access DB replacement.

The proposers literally had no idea of the additional CPU and disk overhead involved in Random Direct Access versus Sequential Access.

They had severe cost and performance problems. The advice they got was to analyse their disk access and pre-sort the input to maximise found in buffer disk reads. We also told them to get rid of PL/I REFER clauses and use fixed Array Bounds since an CPU monitor tool showed that 75% of the CPU time was spent computing offsets of elements affected by REFER clauses.

The project sponsors rejected that advice as proof that we didn't know what we were talking about. When they ran out of excuses and tried it the cost dropped by $1,000 per day.