Premature Optimization
The notion from computer science that one should not spend an inordinate amount of time trying to optimize or refactor code prior to understanding where it becomes clear where the bottlenecks and slowdowns are going to be.
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Origin
The phrase "premature optimization is the root of all evil" was coined by computer scientist Donald Knuth in his 1974 paper "Structured Programming with Go To Statements," published in Computing Surveys. Knuth's full statement was a nuanced warning: programmers, he argued, spent too much time optimizing in the wrong places 97% of the time, at the expense of correctness and clarity. Though Knuth later attributed the observation to C.A.R. Hoare, the preponderance of evidence points to Knuth as the source.
Updated February 22, 2026